High-Performance Broadband Self-Driven Photodetector Based on MoS2/Cs2CuBr4 Heterojunction.

Few-layer transition metal dichalcogenides and perovskites are both promising materials in high-performance optoelectronic devices. Here, we developed a self-driven photodetector by creating a heterojunction between few-layer MoS2 and lead-free perovskite Cs2CuBr4. The detector shows a unique property of very high sensitivity in a broad spectral range of 400 to 800 nm with response speed in a millisecond order. Current-voltage characteristics of the heterojunction device show rectifying behavior, in contrast to the ohmic behavior of the MoS2-based device. The rectifying behavior is attributed to the type II band alignment of the MoS2/Cs2CuBr4 heterojunction. The device shows a broadband (400 to 800 nm) photodetection with very high responsivity reaching up to 2.8 × 104 A/W and detectivity of 1.6 × 1011 Jones at a bias voltage of 3 V. The detector can also operate in self-bias mode with sufficient response. The photocurrent, photoresponsivity, detectivity, and external quantum efficiency of the device are found to be dependent on the illumination power density. The response time of the device is found to be ∼32 and ∼79 ms during the rise and fall of the photocurrent. The work proposes a MoS2/Cs2CuBr4 heterostructure to be a promising candidate for cost-effective, high-performance photodetector.

Monolayer Graphene-MoSSe van der Waals Heterostructure for Highly Responsive Gate-Tunable Near-Infrared-Sensitive Broadband Fast Photodetector.

Transition metal dichalcogenides (TMDCs) are potential two-dimentional materials as natural partners of graphene for highly responsive van der Waals (vdW) heterostructure photodetectors. However, the spectral detection range of the detectors is limited by the optical bandgap of the TMDC, which acts as a light-absorbing medium. Bandgap engineering by making alloy TMDC has evolved as a suitable approach for the development of wide-band photodetectors. Here, broadband (visible to near-infrared) photodetection with high sensitivity in the near-infrared region is demonstrated in a MoSSe/graphene heterostructure. In the ambient environment, the photodetector exhibits high responsivity of 0.6 × 102 A/W and detectivity of 7.9 × 1011 Jones at 800 nm excitation with a power density of 17 fW/µm2 and 10 mV source-drain bias. The photodetector shows appreciable responsivity in self-bias mode due to nonuniform distribution of MoSSe flakes on the graphene layer between the source and drain end and the asymmetry between the two electrodes. Time-dependent photocurrent measurements show fast rise/decay times of ∼38 ms/∼48 ms. A significant gate tunability on the efficiency of the detector has been demonstrated. The device is capable of low power detection and exhibits high operational frequency, gain, and bandwidth. Thus, the MoSSe/graphene heterostructure can be a promising candidate as a high-speed and highly sensitive near-infrared photodetector capable of operating at ambient conditions with low energy consumption.

A rationally designed synthetic antimicrobial peptide against Pseudomonas-associated corneal keratitis: Structure-function correlation.

Contact lens wearers are at an increased risk of developing Pseudomonas-associated corneal keratitis, which can lead to a host of serious ocular complications. Despite the use of topical antibiotics, ocular infections remain a major clinical problem, and a strategy to avoid Pseudomonas-associated microbial keratitis is urgently required. The hybrid peptide VR18 (VARGWGRKCPLFGKNKSR) was designed to have enhanced antimicrobial properties in the fight against Pseudomonas-induced microbial keratitis, including contact lens-related keratitis. In this paper, VR18's modes of action against Pseudomonas membranes were shown by live cell Raman spectroscopy, live cell NMR, live-cell fluorescence microscopy and measures taken using sparsely tethered bilayer lipid membrane bacterial models to be via a bacterial-specific membrane disruption mechanism. The high affinity and selectivity of the peptide were then demonstrated using in vivo, in vitro and ex vivo models of Pseudomonas infection. The extensive data presented in this work suggests that topical employment of the VR18 peptide would be a potent therapeutic agent for the prevention or remedy of Pseudomonas-associated microbial keratitis.

Lattice dynamics of Ge1-xSnx alloy nanowires.

Alloying group IV semiconductors offers an effective way to engineer their electronic properties and lattice dynamics. The incorporation of Sn in Ge permits a transition from an indirect to a direct bandgap semiconductor. Here, by combining polarization, laser power-dependent and temperature-dependent micro-Raman spectroscopy we explore the full lattice dynamics of Ge1-xSnx (x = 0.01, 0.06 and 0.08) alloy nanowires. In the high Sn content samples (x ≥ 0.06), a low-frequency tail and a high-frequency shoulder are observed which are associated with the F2g optical phonon mode of Ge (Ge-Ge mode). The new modes are assigned to the stretching of Ge-Ge bonds due to Sn-induced lattice relaxation and compression, respectively. The symmetry of the observed Raman modes has been studied by polarization-dependent Raman scattering. Nonlinear fitting of the laser power-dependent intensity of the high-frequency Ge-Ge mode in the Ge1-xSnx alloy nanowires with x = 0.06 and 0.08 suggests the activation of a third-order stimulated Raman scattering process, due to the high intensity localized electric field surrounding the Sn clusters. Finally, from the temperature-dependent Raman study, we have estimated the isobaric Grüneisen parameters for all the observed modes.

One-Step Grown Carbonaceous Germanium Nanowires and Their Application as Highly Efficient Lithium-Ion Battery Anodes.

Developing a simple, cheap, and scalable synthetic method for the fabrication of functional nanomaterials is crucial. Carbon-based nanowire nanocomposites could play a key role in integrating group IV semiconducting nanomaterials as anodes into Li-ion batteries. Here, we report a very simple, one-pot solvothermal-like growth of carbonaceous germanium (C-Ge) nanowires in a supercritical solvent. C-Ge nanowires are grown just by heating (380-490 °C) a commercially sourced Ge precursor, diphenylgermane (DPG), in supercritical toluene, without any external catalysts or surfactants. The self-seeded nanowires are highly crystalline and very thin, with an average diameter between 11 and 19 nm. The amorphous carbonaceous layer coating on Ge nanowires is formed from the polymerization and condensation of light carbon compounds generated from the decomposition of DPG during the growth process. These carbonaceous Ge nanowires demonstrate impressive electrochemical performance as an anode material for Li-ion batteries with high specific charge values (>1200 mAh g-1 after 500 cycles), greater than most of the previously reported for other "binder-free" Ge nanowire anode materials, and exceptionally stable capacity retention. The high specific charge values and impressively stable capacity are due to the unique morphology and composition of the nanowires.

Growth and analysis of the tetragonal (ST12) germanium nanowires.

New semiconducting materials, such as state-of-the-art alloys, engineered composites and allotropes of well-established materials can demonstrate unique physical properties and generate wide possibilities for a vast range of applications. Here we demonstrate, for the first time, the fabrication of a metastable allotrope of Ge, tetragonal germanium (ST12-Ge), in nanowire form. Nanowires were grown in a solvothermal-like single-pot method using supercritical toluene as a solvent, at moderate temperatures (290-330 °C) and a pressure of ∼48 bar. One-dimensional (1D) nanostructures of ST12-Ge were achieved via a self-seeded vapour-liquid-solid (VLS)-like paradigm, with the aid of an in situ formed amorphous carbonaceous layer. The ST12 phase of Ge nanowires is governed by the formation of this carbonaceous structure on the surface of the nanowires and the creation of Ge-C bonds. The crystalline phase and structure of the ST12-Ge nanowires were confirmed by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy. The nanowires produced displayed a high aspect ratio, with a very narrow mean diameter of 9.0 ± 1.4 nm, and lengths beyond 4 µm. The ST12-Ge nanowire allotrope was found to have a profound effect on the intensity of the light emission and the directness of the bandgap, as confirmed by a temperature-dependent photoluminescence study.

Solution phase growth and analysis of super-thin zigzag tin selenide nanoribbons.

Tin selenide (SnSe), a highly promising layered material, has been garnering particular interest in recent times due to its significant promise for future energy devices. Herein we report a simple solution-phase approach for growing highly crystalline layered SnSe nanoribbons. Polyvinylpyrrolidone (PVP) was used as a templating agent to selectively passivates the (100) and (001) facets of the SnSe nanoribbons resulting in the unique growth of nanoribbons along theirb-axis with a defined zigzag edge state along the sidewalls. The SnSe nanoribbons are few layers thick (∼20 layers), with mean widths of ∼40 nm, and achievable length of >1µm. Nanoribbons could be produced in relatively high quantities (>150 mg) in a single batch experiment. The PVP coating also offers some resistance to oxidation, with the removal of the PVP seen to lead to the formation of a SnSe/SnOxcore-shell structure. The use of non-toxic PVP to replace toxic amines that are typically employed for other 1D forms of SnSe is a significant advantage for sustainable and environmentally friendly applications. Heat transport properties of the SnSe nanoribbons, derived from power-dependent Raman spectroscopy, demonstrate the potential of SnSe nanoribbons as thermoelectric material.

Polymer-Protein Hybrid Network Involving Mucin: A Mineralized Biomimetic Template for Bone Tissue Engineering.

Biomimetic matrices offer a great advantage to understand several biological processes including regeneration. The study involves the development of a hybrid biomimetic scaffold and the uniqueness lies in the use of mucin, as a constituent protein. Through this study, the role of the protein in bone regeneration is deciphered through its development as a 3D model. As a first step towards understanding the protein, the interactions of mucin and collagen are determined by in silico studies considering that collagen is the most abundant protein in the bone microenvironment. Both proteins are reported to be involved in bone biology though the exact role of mucin is a topic of investigation. The in silico studies of collagen-mucin suggest to have a proper affinity toward each other, forming a strong basis for 3D scaffold development. The developed 3D scaffold is a double network system comprising of mucin and collagen and vinyl end functionalized polyethylene glycol. In situ deposition of mineral crystals has been performed enzymatically. Biological evaluation of these mineral deposited scaffolds is done in terms of their bone regeneration potential and a comparison of the two systems with and without mineral deposition is presented.

Probing dipole and quadrupole resonance mode in non-plasmonic nanowire using Raman spectroscopy.

Electric field enhancement in semiconductor nanostructures offers a possibility to find an alternative to the metallic particles which is well known for tuning the light-matter interaction due to its strong polarizability and size-dependent surface plasmon resonance energy. Raman spectroscopy is a powerful technique to monitor the electric field as its scattering depends on the electromagnetic eigenmode of the particle. Here, we observe enhanced polarized Raman scattering from germanium nanowires of different diameters. The incident electromagnetic radiation creates a distribution of the internal electric field inside the naowires which can be enhanced by manipulating the nanowire diameter, the incident electric field and its polarization. Our estimation of the enhancement factor, including its dependence on nanowire diameter, agrees well with the Mie theory for an infinite cylinder. Furthermore, depending on diameter of nanowire and wavelength of incident radiation, polarized Raman study shows dipolar (antenna effect) and quadrupolar resonances, which has never been observed in germanium nanowire. We attempt to understand this polarized Raman behavior using COMSOL Multiphysics simulation, which suggests that the pattern observed is due to photon confinement within the nanowires. Thus, the light scattering direction can be toggled by tuning the polarization of incident excitation and diameter of non plasmonic nanowire.

Sequence specificity of amylin-insulin interaction: a fragment-based insulin fibrillation inhibition study.

Subcutaneous insulin delivery serves as the major treatment for the ever-increasing spread of type II diabetes worldwide. However, long-term exposure to insulin results in local aggregates at the site of injection. This therapeutic concern accentuates the need to develop newer effective excipients to stabilize the insulin in pharmaceutical formulations. The fact that in normal physiological conditions, insulin interacts with the amylin hormone co-secreted from the pancreas, we targeted a peptide-mimetic approach based on the amylin sequence. The amylin-fibrillating core (NL6- N22FGAIL27 from the human Islet Amyloid Poly-Peptide) and its derivative NFGAXL (NL6X, X = 2-aminobenzoic acid) were used as potential inhibitory peptides against insulin amyloidogenesis. The fibrillation kinetics in the presence of the inhibitors was studied using an array of biophysical and microscopic techniques. High-resolution NMR spectroscopy enabled probing of the inhibitory interaction at an atomic resolution. Our results highlight the potential of using the naturally evolved NL6 peptide as an effective inhibitor against insulin fibrillation.

Investigation of the Origin of Voltage Generation in Potentized Homeopathic Medicine through Raman Spectroscopy.

BACKGROUND: For the study of homeopathic medicines in proper perspective, emerging techniques in material science are being used. Vibrational spectroscopy is one such tool for providing information on different states of hydrogen bonding as an effect of potentization. The associated change in electrical properties is also correlated with this effect. OBJECTIVE: From the vibrational spectra, the changes in hydrogen bonding due to dilution followed by unidirectional vigorous shaking (together termed potentization) of 91% ethanol and two homeopathic medicines Chininum purum and Acidum benzoicum have been studied. The aim was to correlate the result with the change in the electrical properties of the system. METHODS: Raman spectroscopy was used to study the vibrational spectra. A U-shaped glass tube (electrochemical cell), where one arm contained bi-distilled water and the other arm alcohol/homeopathic medicine (the arms being separated by a platinum foil), was used to measure the voltage generated across two symmetrically placed platinum electrodes. RESULTS: For all samples, it was observed that potentization affected the intensity of OH stretching bands at the frequencies 3240 cm-1, 3420 cm-1 and 3620 cm-1, corresponding to strong hydrogen bond, weak hydrogen bond and broken hydrogen bond, respectively. With the increase in potency, in the presence and absence of the two medicines in ethanol, the number of OH groups linked by strong hydrogen bonds decreased, while the number of OH groups with weak hydrogen bonds increased. With the increase in potentization, the number of OH groups with broken hydrogen bonds showed a difference in the presence and absence of the medicine.The voltage measurements for ethanol show that, with succussion, the magnitude of voltage increased with the two medicines at lower potencies, but not at higher potency where the voltage is lower. Acidum benzoicum, which is acidic in nature, had higher voltage values (113mV, 130 mV and 118 mV at 6C, 30C and 200C, respectively), compared with Chininum purum, which is basic in nature (20 mV, 85 mV and 65 mV at 6C, 30C and 200C, respectively). CONCLUSION: The experimental results indicate a correlation between the vibrational and electrical properties of the homeopathic medicines Acidum benzoicum and Chininum purum at different potencies.

Au nanoparticles functionalized 3D-MoS2 nanoflower: An efficient SERS matrix for biomolecule sensing.

Fabrication of Molybdenum disulfide (MoS2) nanostructures and surface functionalization with noble metal nano particles is an emerging field of research as it has potential applications in electronic devices and chemical sensing. Here we report application of gold nanoparticles (AuNPs) decorated MoS2 nanoflowers (Au-MoS2 NFs) as an efficient bio-sensor. MoS2 NFs, synthesized using green synthesis process, are further functionalized with AuNPs to tune their physical properties and make them more appropriate for biological applications. The abundant 'hot-spots' created by AuNPs through localization of electromagnetic field endows the Au-MoS2 hybrid structure as an excellent substrate for biochemical sensing through surface enhanced Raman scattering (SERS). The sensing efficiency of the SERS substrate is examined using Rh6G as probe molecule with concentration as low as 10-12 M. Main emphasis is given in detecting free bilirubin, an important component of human blood, using SERS technique. Au-MoS2 NF SERS substrate exhibits high sensitivity, stability and excellent reproducibility in sensing bilirubin from high level (10-3 M) to picomolar level. The concentration (C) dependent SERS intensity (I) is found to follow the general relationship I = Cα, with α ranging from 0.09 to 0.12. The substrate shows excellent selectivity and reliability while sensing of free bilirubin performed in human serum in the presence of crucial interferences such as dextrose, cholesterol and phosphate. In the present study, this Au-MoS2 hybrid offers a new potential biosensing technology for free bilirubin detection and is anticipated to be applied for clinic diagnosis.

Development of a 2-Nitrobenzoate-Sensing Bioreporter Based on an Inducible Gene Cluster.

Based on the sole information of structural genes of the 2-nitrobenzoate (2NBA) utilizing catabolic gene cluster (onbX1X2FCAR1EHJIGDBX3), 2NBA-sensing bioreporters were constructed by incorporating egfp into the onb gene cluster of Cupriavidus sp. strain ST-14. Incorporation of reporter gene in proximal to the hypothesized promoter region in conjunction with the disruption of the gene encoding inducer-metabolizing enzyme was turned out to be advantageous in reporter gene expression at low inducer concentration. The bioreporter strain was capable of expressing EGFP from the very 1st hour of induction and could detect 2NBA at (sub) nanomolar level exhibiting a strict specificity toward 2NBA, displaying no response to EGFP expression from its meta- and para-isomers as well as from a number of structurally related compounds. The present study is a successful demonstration of the development of a 2NBA-sensing bioreporter with respect to ease of construction, inducer specificity, and sensitivity, without prior knowledge of the associated inducer-responsive promoter-regulator elements. The present approach can be used as a model for the development of bioreporters for other environmental pollutants.

Hygroscopic Coating of Sulfuric Acid Shields Oxidant Attack on the Atmospheric Pollutant Benzo(a)pyrene Bound to Model Soot Particles.

Substantial impacts on climate have been documented for soot‒sulfuric acid (H2SO4) interactions in terms of optical and hygroscopic properties of soot aerosols. However, the influence of H2SO4 on heterogeneous chemistry on soot remains unexplored. Additionally, oxidation rate coefficients for polycyclic aromatic hydrocarbons intrinsic to the atmospheric particles evaluated in laboratory experiments seem to overestimate their degradation in ambient atmosphere, possibly due to matrix effects which are hitherto not mimicked in laboratory experiments. For the first time, our kinetics study reports significant influence of H2SO4 coating on heterogeneous ozonation of benzo(a)pyrene (BaP) deposited on model soot, representative to atmospheric particles. The approximate specific surface area of model soot (5 m2g-1) was estimated as a measure of the availability of surface molecules to a typical gaseous atmospheric oxidant. Heterogeneous bimolecular reaction kinetics and Raman spectroscopy studies suggested plausible reasons for decreased BaP ozonation rate in presence of H2SO4: 1. decreased partitioning of O3 on soot surface and 2. shielding of BaP molecules to gaseous O3 by acid-BaP reaction or O3 oxidation products.

Plasmon mediated enhancement and tuning of optical emission properties of two dimensional graphitic carbon nitride nanosheets.

We demonstrate surface plasmon induced enhancement and tunablilty in optical emission properties of two dimensional graphitic carbon nitride (g-C3N4) nanosheets through the attachment of gold (Au) nanoparticles. Raman spectroscopy has revealed surface enhanced Raman scattering that arises due to the combined effect of the charge transfer process and localized surface plasmon induced enhancement in electromagnetic field, both occurring at the nanoparticle-nanosheet interface. Photoluminescence studies suggest that at an optimal concentration of nanoparticles, the emission intensity can be enhanced, which is maximum within the 500-525 nm region. Further, the fabricated electroluminescent devices reveal that the emission feature can be tuned from bluish-green to red (∼160 nm shift) upon attaching Au nanoparticles. We propose that the π*→π transition in g-C3N4 can trigger surface plasmon oscillation in Au, which subsequently increases the excitation process in the nanosheets and results in enhanced emission in the green region of the photoluminescence spectrum. On the other hand, electroluminescence of g-C3N4 can induce plasmon oscillation more efficiently and thus can lead to red emission from Au nanoparticles through the radiative damping of particle plasmons. The influence of nanoparticle size and coverage on the emission properties of two dimensional g-C3N4, nanosheets has also been studied in detail.

Photoresponse of a Single Y-Junction Carbon Nanotube.

We report investigation of optical response in a single strand of a branched carbon nanotube (CNT), a Y-junction CNT composed of multiwalled CNTs. The experiment was performed by connecting a pair of branches while grounding the remaining one. Of the three branch combinations, only one combination is optically active which also shows a nonlinear semiconductor-like I-V curve, while the other two branch combinations are optically inactive and show linear ohmic I-V curves. The photoresponse includes a zero-bias photocurrent from the active branch combination. Responsivity of ≈1.6 mA/W has been observed from a single Y-CNT at a moderate bias of 150 mV with an illumination of wavelength 488 nm. The photoresponse experiment allows us to understand the nature of internal connections in the Y-CNT. Analysis of data locates the region of photoactivity at the junction of only two branches and only the combination of these two branches (and not individual branches) exhibits photoresponse upon illumination. A model calculation based on back-to-back Schottky-type junctions at the branch connection explains the I-V data in the dark and shows that under illumination the barriers at the contacts become lowered due to the presence of photogenerated carriers.

Non-equilibrium induction of tin in germanium: towards direct bandgap Ge(1-x)Sn(x) nanowires.

The development of non-equilibrium group IV nanoscale alloys is critical to achieving new functionalities, such as the formation of a direct bandgap in a conventional indirect bandgap elemental semiconductor. Here, we describe the fabrication of uniform diameter, direct bandgap Ge(1-x)Sn(x) alloy nanowires, with a Sn incorporation up to 9.2 at.%, far in excess of the equilibrium solubility of Sn in bulk Ge, through a conventional catalytic bottom-up growth paradigm using noble metal and metal alloy catalysts. Metal alloy catalysts permitted a greater inclusion of Sn in Ge nanowires compared with conventional Au catalysts, when used during vapour-liquid-solid growth. The addition of an annealing step close to the Ge-Sn eutectic temperature (230 °C) during cool-down, further facilitated the excessive dissolution of Sn in the nanowires. Sn was distributed throughout the Ge nanowire lattice with no metallic Sn segregation or precipitation at the surface or within the bulk of the nanowires. The non-equilibrium incorporation of Sn into the Ge nanowires can be understood in terms of a kinetic trapping model for impurity incorporation at the triple-phase boundary during growth.

Peanut proteins in periodate specific anion sensing: An ensuing reduction in allergic response.

Peanut proteins conarachin II, conarachin I and arachin were found to behave as highly selective fluorescence sensors for periodate amongst a set of different anions. The interactions of the proteins with periodate were also confirmed by other spectral methods and enzyme linked immunosorbent assay (ELISA). The results indicate a selective interaction of peanut proteins with periodate amongst chloride, sulphate, iodide, phosphate, nitrate, nitrite, bromide, fluoride, persulphate, acetate, thiosulphate, arsenite, arsenate, sulphite, and iodide. Periodate sensing using different synthesized organic molecules are already reported in the literature. In this article we report the efficiency of peanut proteins as anion sensor which are bioactive and inexpensive too. The protein periodate interactions have also resulted in a simultaneous reduction in allergenicity of the peanut proteins. A change in the secondary structure of the protein was found responsible for this change which was further established with the help of circular dichroism and Raman spectroscopy.

Raman spectroscopy shows difference in drugs at ultrahigh dilution prepared with stepwise mechanical agitation

OBJECTIVE: The present study aims at deciphering the nature of the water structure of two ultrahigh diluted (UHD) homeopathic drugs by Laser Raman Spectroscopy. METHOD: Two homeopathic drugs Sulphur and Natrum mur in three UHD 30cH, 200cH and 1000cH were selected for the study. Raman spectra of the drugs and their medium (90% ethanol) were obtained in the wave number region of 2600-3800 cm-1. The intensity ratio at vibration frequencies between 3200 and 3420 (R1) and that between 3620 and 3420 (R2) was calculated for each UHD as well as the control. RESULTS: Raman spectra shows differences in intensities in different UHDs and their control in the stretching vibrations of CH and OH groups. The three UHDs of each drug show an inverse relationship with respect to the R1 values. However, for R2 the relationship of UHD for each drug is positive. CONCLUSION: R1 provides information about the relative number of OH groups with strong and weak hydrogen bonds. R2 suggests the relative number of OH groups with broken and weak hydrogen bonds. Judged from R1 values the lower is the rank of UHD, the stronger is the H-bond of the OH groups. In the light of R2 values, the higher is the UHD rank the more abundant is the free OH groups. So, hydrogen bond strength and free OH groups together make an effective UHD rank relating to Sulphur and Natrum mur.

Raman spectroscopy reveals variation in free OH groups and hydrogen bond strength in ultrahigh dilutions

OBJECTIVE: To decipher the nature of water structure in two ultrahigh diluted (UHD) homeopathic drugs by Laser Raman Spectroscopy. METHOD: Two homeopathic drugs Calcarea carbonica (Calc.) and Sepia officinalis (Sep.) in 8cH, 202cH, and 1002cH and their diluent medium 90% ethanol in 8cH and 202cH were used in the present study. Laser Raman spectra of all the samples were obtained in the wave number region of 2400 – 4200 cm-1. The intensity ratio at vibration frequencies between 3200 and 3420 (R1) and that between 3620 and 3420 (R2) were calculated for each UHD of the samples. RESULTS: The spectra show a marked difference in intensities in the stretching vibrations of CH and OH groups of all the samples. R1 values for three UHDs of Calc. and Sep. show negative and positive relationships, respectively. In the case of R2 values, the relationship in three UHDs is 81002 for Calc., and 8> 202 < 1002 for Sep. In the case of control (ethanol UHDs) both R1 and R2 show a negative relationship. CONCLUSION: R1 denotes a relative number of OH groups with strong and weak hydrogen bonds. R2 indicates the relative number of OH groups with broken and weak H-bonds. Therefore, the UHDs of the two drugs and the control are different from each other with respect to hydrogen bond strength of OH groups and the number of free OH groups or non-hydrogen bonded water molecules.