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A series of attempts to enhance the bioavailability of water insoluble drugs have been made by the fine grinding technique using a planetary ball mill in wet milling process. Here, the possibility of improving the dissolution properties of water insoluble drugs such as ursodeoxycholic acid (UDCA), diphenyl hydrantoin (phenytoin) and biphenyl dimethyl dicarboxylate (DDB) based on ultra-fine grinding process has been discussed with comparison to experimental data. Also examined was the intrinsic bioavailability estimated based on a molecular modeling approach and thermo- physical data.

We performed grand canonical Monte Carlo simulations on the series of MOFs, that are Metal-Organic Frameworks having various organic linkers and nanocube frameworks, to find out rational design and synthetic strategies toward efficient hydrogen storage materials. The adsorption amounts of hydrogen molecules showed diverse range according to the variation of parameter values. This indicated that the hydrogen adsorption was sensitive to the values of parameters corresponding to the non-bonding interactions. The optimization of the parameters was done to fit the experimental results at 77 K. After the parameterization of the potential function, we adopted this condition to predict the adsorption amount of hydrogen molecules on IRMOF-3, which has NH2 group as the substituent of hydrogen bonded to benzene ring. The calculation results showed good agreement with experimental adsorptions and we analyzed the adsorption sites of each MOF and the relationship between the adsorption characteristics and the hydrogen uptake capacity.

We have investigated the relationship between the molecular structures of metal-organic frameworks (MOFs) and their hydrogen uptake capabilities. Quantitative structure–property analysis was used to find out MOF structural factors important for hydrogen adsorption. To determine the quantitative interaction strength between hydrogen molecules and MOFs, the iso-value surface area of electrostatic potential was developed as a new descriptor. Quantitative analysis of structurally similar MOFs showed that the functionalization of aromatic organic linkers could induce noticeable polarization effect on the framework surface. We also found that the topology of MOFs plays an important role in determining the amount of ultimate hydrogen uptake. Through this quantitative structure–uptake relationship analysis, structural descriptors for the prediction of MOF hydrogen sorption capacity have been identified.

Hydrogen adsorption mechanism into MOF-5, a porous metal-organic framework (MOF) has been studied by density functional theory calculation. The selected functionals for the prediction of interaction energies between hydrogen and potential adsorption sites of MOF-5 were utilized after the evaluation with the various functionals for interaction energy of H 2 ⋯C 6 H 6 model system. The adsorption energy of hydrogen molecule into MOF-5 was investigated with the consideration of the favorable adsorption sites and the orientations. We also calculated the second favorable adsorption sites by geometry optimization using every combination of two first adsorbed hydrogen molecules. Based on the calculation of the first and the second adsorption sites and energies, it has been suggested that the hydrogen adsorption into MOF-5 follows a cooperative mechanism in which the metal sites initiate the propagation of the hydrogen adsorption on the whole frameworks. In addition, the interaction mode between the simple benzene ring with hydrogen is significantly changed when the benzene ring has been incorporated into the framework of MOF-5.

Amylosucrase (ASase; EC 2.4.1.4) synthesizes α-1,4-glucans using sucrose as a sole substrate. The aim of this study was to compare the enzymatic properties of four recombinant ASase genes to determine the underlying mechanisms thereof. Following cloning and expression in Escherichia coli, we determined that the ASase enzyme from Deinococcus geothermalis (DGAS) had the highest thermostability whereas ASase from Neisseria polysaccharea (NPAS) showed the greatest polymerization activity. Chimeric ASases were constructed using dgas and npas genes by overlap extension polymerase chain reaction. Two of the six chimeric ASases generated, NPAS-B' and DGAS-B, showed ASase activity using sucrose as the sole substrate. However, DGAS-B was not able to produce longer α-1,4-glucans; the highest degree of polymerization was

Among recently synthesized isoreticular metal-organic frameworks (IRMOFs), interpenetrating IRMOFs show high hydrogen adsorption capacities at low temperature and under ambient pressure. However, little is known about the molecular basis of their hydrogen binding properties. In this work, we performed grand canonical Monte Carlo (GCMC) simulations to investigate the effect of catenation on the interactions between hydrogen molecules and IRMOFs. We identified the adsorption sites and analyzed the adsorption energy distributions. The simulation results show that the small pores generated by catenation can play a role to confine the hydrogen molecules more densely, so that the capacity of the interpenetrating IRMOFs could be higher than that of the non-interpenetrating IRMOFs.

Molecular dynamics simulations with an umbrella potential function in solution were carried out to obtain the potential of mean force for sodium-dimethyl phosphate (Na + -DMP − ) and sodium-methyl phosphate (Na + -MP 2− ). The Na + -DMP − showed two minima in pmf profile, a less stable minimum of ca. 3.5 A and a more stable minimum of ca. 5.0 A, resulting in direct and indirect contact between two ions. On the other hand, the Na + -MP 2− showed one prominent minimum in pmf profile, at approximately ca. 4.5 A. Water molecules around Na + -DMP − better formed a hydrogen-bonded network than around Na + -MP 2− , showing a stronger interaction between water and the Na + -MP 2− .

Using molecular dynamics simulations with the rigid TIP4P water model, we have analyzed the structural change of liquid water induced by an external electric field. The temperature was controlled with a Nose–Hoover thermostat. In this paper, we report the acquisition of liquid water with the enhanced structural regularity by applying an electric field. From the simulations under various strengths of the electric field, we can see that the threshold for the significant structural change is thought to be between 0.2 and 0.15 V/A. When the number of six-membered rings is increased by the external electric field, so that water is forced to have structural regularity, we calculate the diffusion coefficients and discover that water we make in the simulations is not solid but still liquid under the electric field.

In order to study the antifreezing mechanism of the HPLC6 antifreeze protein and its structural effects on the antifreezing activity, molecular dynamics simulations for this protein in aqueous solution were carried out at two different temperatures (300 K and 253 K). The results of these simulations showed that the binding mechanism of the antifreeze protein is mainly due to the adsorption of the molecule to the ice crystal surface and thereby inhibiting the ice growth. The hydrogen bonds between the threonine residues and the oxygen atoms in the ice play an important role in this mechanism. Mutation study was carried out to verify the mechanism. In addition, hydrophobic alanine residues are located on the opposite side of threonine residues and they repel water molecules to prevent water molecules from approaching the ice surface.

The hyperthermostable protein rubredoxin from Pyrococcus furiosus is a 53-residue protein with a three-stranded antiparallel β-sheet and several loops. In this paper, the hydrophobic interaction of residues on the surface of the protein was investigated as well as electrostatic interactions between residues. To investigate the effect of changes of electrostatic and hydrophobic interactions on the structure and the dynamic property of P. furiosus rebredoxin, molecular dynamics simulations in solution were performed on three mesophilic rubredoxins, P. furiosus rubredoxin, and five mutants of P. furiosus rubredoxin. Glu 14 of P. furiosus has a backbone hydrogen bond with N-terminal and multiple electrostatic interactions with Ala 1, Trp 3, and Phe 29. The multiple electrostatic interactions make the residues around the N-terminal stable, and the hydrogen bond between Glu 14 and Ala 1 remains even at high temperature. The flexibility of a loop from Asp 15 to Gly 26 is reduced by making the loop closer to the ...

Maltose-forming α-amylase is a glycoside hydrolase family 57 (GH57) member that is unique because it displays dual hydrolysis activity toward α-1,4- and α-1,6-glycosidic linkages and only recognizes maltose. This enzyme was previously identified only in Pyrococcus sp. ST04 (PSMA); however, we recently found two homologs subgroups in Thermococcus species. One subgroup (subgroup A) showed relatively high amino acid sequence similarity to PSMA (>71%), while the other subgroup (subgroup B) showed lower homology with PSMA (

We have used grand canonical Monte Carlo simulations with a first-principles-based force field to show that metal–organic frameworks (MOFs) with Li functional groups (i.e. CLi bonds) allow for exceptional H2 uptake at ambient temperature. For example, at 298 K and 100 bar, IRMOF-1-4Li shows a total H2 uptake of 5.54 wt % and MOF-200-27Li exhibits a total H2 uptake of 10.30 wt %, which are much higher than the corresponding values with pristine MOFs. Li-functionalized MOF-200 (MOF-200-27Li) shows 11.84 wt % H2 binding at 243 K and 100 bar. These hydrogen-storage capacities exceed the 2015 DOE target of 5.5 wt % H2. Moreover, the incorporation of Li functional groups into MOFs provides more benefits, such as higher delivery amount, for H2 uptake than previously reported Li-doped MOFs.

Using phage display technique, we identified tissue-targeting peptide sets that recognize specific tissues (bone-marrow dendritic cell, kidney, liver, lung, spleen and visceral adipose tissue). In order to rapidly evaluate tissue-specific targeting peptides, we performed machine learning studies for predicting the tissue-specific targeting activity of peptides on the basis of peptide sequence information using four machine learning models and isolated the groups of peptides capable of mediating selective targeting to specific tissues. As a representative liver-specific targeting sequence, the peptide “DKNLQLH” was selected by the sequence similarity analysis. This peptide has a high degree of homology with protein ligands which can interact with corresponding membrane counterparts. We anticipate that our models will be applicable to the prediction of tissue-specific targeting peptides which can recognize the endothelial markers of target tissues.

The hydrogen spillover mechanism has been discussed in the field of hydrogen storage and is believed to have particular advantage over the storage as metal or chemical hydrides. We investigate conditions for practicality realizing the hydrogen spillover mechanism onto carbon surfaces, using first-principles methods. Our results show that contrary to common belief, types of hydrogenation configurations of graphene (the aggregated all-paired configurations) can satisfy the thermodynamic requirement for room-temperature hydrogen storage. However, the peculiarity of the paired adsorption modes gives rise to a large kinetic barrier against hydrogen migration and desorption. It means that an extremely high pressure is required to induce the migration-derived hydrogenation. However, if mobile catalytic particles are present inside the graphitic interstitials, hydrogen migration channels can open and the spillover phenomena can be realized. We suggest a molecular model for such a mobile catalyst which can exchange hydrogen atoms with the wall of graphene.

In order to develop a computational method to rapidly evaluate transdermal peptides, we report approaches for predicting the transdermal activity of peptides on the basis of peptide sequence information using Artificial Neural Network (ANN), Partial Least Squares (PLS) and Support Vector Machine (SVM). We identified 269 transdermal peptides by the phage display technique and use them as the positive controls to develop and test machine learning models. Combinations of three descriptors with neural network architectures, the number of latent variables and the kernel functions are tried in training to make appropriate predictions. The capacity of models is evaluated by means of statistical indicators including sensitivity, specificity, and the area under the receiver operating characteristic curve (ROC score). In the ROC score-based comparison, three methods proved capable of providing a reasonable prediction of transdermal peptide. The best result is obtained by SVM model with a radial basis function and VHSE descriptors. The results indicate that it is possible to discriminate between transdermal peptides and random sequences using our models. We anticipate that our models will be applicable to prediction of transdermal peptide for large peptide database for facilitating efficient transdermal drug delivery through intact skin.

We present a low-cost WDM-PON employing colorless uncooled RSOA-based spectrum sliced sources. Colorless operations over 32 WDM channels are demonstrated from 0 to 60 o C in 155-Mb/s transmissions over 25 km.

A WDM-PON with 50-GHz channel spacing employing RSOA-based spectrum sliced sources is presented. Colorless operations over 32 DWDM channels are demonstrated from -10 to 80 °C in 155-Mb/s transmissions over 10 km.

In order to investigate the reason for the higher capacity of the interpenetrating isoreticular metal-organic frameworks (IRMOFs) at lower temperatures, we performed grand canonical Monte Carlo (GCMC) simulations and molecular dynamics simulations at 77 K for a set of the interpenetrating IRMOF-11 and the non-interpenetrating counterpart IRMOF-12. From the GCMC simulations, we found universal force field (UFF) is better for describing the hydrogen adsorption behavior than DREIDING force field. The results from the molecular dynamics simulations showed the density of adsorbed hydrogen molecules was increased in the various pores created by the catenation of IRMOF comparing to that of the pores in IRMOF-12. Moreover, the adsorbed hydrogen molecules in IRMOF-11 have the smaller diffusion coefficients. It means that their dynamic behavior is more restricted because of the complexity of the interpenetrating network of IRMOF-11. These results of molecular simulations show the small pores created by the catenation are important for the increase of hydrogen adsorption on IRMOF-11 at lower temperatures.

We developed polarization-independent high-power superluminescent diodes (SLDs) for wavelength division multiplexed-passive optical network (WDM-PON) applications. The SLD presents CW output power of 150 mW, spectral bandwidth of 40 nm, polarization-dependent power variation of less than 1 dB, and spectral ripple of 3 dB at current of 1.47 A and temperature of 25 degC

New yellow-green emitting materials using bis(dipyrrinato)zinc complex moiety were synthesized by substituting phenyl group and 1- or 2-positioned naphthalene group. Bis[5-(1-naphthalenyl)-dipyrrinato]zinc complex (Zn(1-NaPN)2) substituted at position 1 of naphthalene group showed about 10 times stronger photoluminescence (PL) property and sharper PL spectrum compared to bis[5-(phenyl)-dipyrrinato]zinc complex (Zn(PPN)2) and bis[5-(2-naphthalenyl)-dipyrrinato]zinc complex (Zn(2-NaPN)2). Optical properties in film state were almost identical to the result of non-doped organic light emitting diodes (OLEDs) device. Luminance efficiency (cd/A) of Zn(1-NaPN)2 was 0.33 cd/A, which was about 4∼8 times higher than Zn(PPN)2, 0.04 cd/A and Zn(2-NaPN)2, 0.08 cd/A. Quantum efficiency was also about 2∼3 times higher.

A 50 GHz-spaced spectrum-slicing wavelength division multiplexed (WDM) passive optical network (PON) employing uncooled RSOA is presented. 32-channel coverage and colourless operation over 90degC temperature range are demonstrated at 155 Mbit/s

An optical fault monitoring method in WDM-PON using a broadband light source is demonstrated. This method can achieve real-time fault monitoring for WDM channels. In addition, the optical line terminal can distinguish transmission fibre fault from upstream transmitter failure in the optical network unit.

Thermal reliability of an uncooled Fabry-Perot laser diode (F-PLD) wavelength-locked to spectrum-sliced amplified spontaneous emission (ASE) as a source for wavelength division multiplexed-passive optical networks (WDM-PONs) is presented. An F-PLD with narrow mode spacing and asymmetric facet reflectivity relieved temperature dependency of transmission and power requirement of ASE injection. The chip temperature range of error-free transmission at 155 Mbit/s extended over 70°C with −22 dBm ASE injection.