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Current
Nanoscience
ISSN: 1573-4137
Current Nanoscience
Volume 5, Number 4, November 2009
Contents
Enhancement of Human Bone Marrow Cell Uptake of Quantum Dots
using Tat Peptide Pp. 390-395
Berry C.C., Harianawalw H., Loebus J., Oreffo R.O.C. and
de la Fuente J.
[Abstract] [Full
Text Article]
State of the Art of Nanobiotechnology
Applications in Neglected Diseases Pp. 396-408
Nelson Durán, Priscyla D. Marcato, Zaine Teixeira,
Marcela Durán, Fabio T.M. Costa and Marcelo
Brocchi
[Abstract] [Full
Text Article]
Polymerosomes of PCL and PEG Demonstrate
Enhanced Therapeutic Efficacy of Insulin Pp. 409-416
Rachna Rastogi, Sneh Anand and Veena
Koul
[Abstract] [Full
Text Article]
Formulation of Nanosuspensions as a New
Approach for the Delivery of Poorly Soluble Drugs Pp.
417-427
Xiaohui Pu, Jin Sun, Mo Li and Zhonggui
He
[Abstract] [Full
Text Article]
Preparation and Characterization of Oil
in Water Nano-Reservoir Systems for Improved Oral Delivery
of Atorvastatin Pp. 428-440
Gulam Mustafa, Zeenat I. Khan, Tripta Bansal
and Sushama Talegaonkar
[Abstract] [Full
Text Article]
Recent Advances in Nanoneurology for
Drug Delivery to the Brain Pp. 441-448
Jagat R. Kanwar, Ganesh Mahidhara and Rupinder
K. Kanwar
[Abstract] [Full
Text Article]
Two Novel Freeze-Dried pH-Sensitive Cyclosporine
A Nanoparticles: Preparation, in vitro Drug Release,
and in vivo Absorption Enhancement Effects Pp.
449-456
Fang Zhi-gang, Pan Ping, Yang Zhi-qiang, Chen
Ya-gen, Zhang Jian-kang, Wei Miao, Zhang Xue-nong and
Zhang Qiang
[Abstract] [Full
Text Article]
Self-Assembly from Low Dimension to Higher
Conformation of GGX Motif in Spider Silk Protein Pp.
457-464
Qinghan Zhou, Juan Lin, Feng Yuan, Zhaoyang Ye,
Feng Qiu, Chengkang Tang, Yongzhu Chen and Xiaojun
Zhao
[Abstract] [Full
Text Article]
Nano-Mechanics and Membrane Receptor
Mapping of CD8+
T Cells Pp. 465-469
Yangzhe Wu, Yi Hu, Hongsong Lu, Jiye Cai, Xianhui He and
Hongxia Zhao
[Abstract] [Full
Text Article]
A Convenient Synthesis Route to the Zinc
Metagermanate Nanorods Pp. 470-473
L. Z. Pei, J. F. Wang, W. Tan, H. Y. Yu, C. G. Fan, J.
Chenand Qian-Feng Zhang
[Abstract] [Full
Text Article]
A Surfactant-Free, Precursor-Induced
Method to Flower-Like ZnO Nanostructures Pp. 474-478
Lin Kong, Jia-Xiang Yang, Hong-Ping Zhou, Yu-Peng
Tian, Jie-Ying Wu and Bao-Kang Jin
[Abstract] [Full
Text Article]
ZnO Nanowires from Nanopillars: Influence
of Growth Time Pp. 479-484
P. Sangpour, M. Roozbehi, O. Akhavan and A.Z.
Moshfegh
[Abstract] [Full
Text Article]
Microwave Rapid Synthesis of Nanoporous
Fe3O4
Magnetic Microspheres Pp. 485-488
Da-Peng Yang, Feng Gao, Da-Xiang Cui and
Mo Yang
[Abstract] [Full
Text Article]
Fabrication and Phase Transformation
in Crystalline Nanoparticles of PbZrO3
Derived By Sol-Gel Pp. 489-492
Satyendra Singh and S.B. Krupanidhi
[Abstract] [Full
Text Article]
Investigation on the Behaviour of Sputter-Deposited
Nanocrystalline Cr3Si
Film by Double Cathode Glow Discharge Pp. 493-502
Jiang Xu
[Abstract] [Full
Text Article]
C20,
C24 and C26
Nanocrystal Series Pp. 503-505
Zhenxia Wang , Cuilan Ren, Zhenzhong Yong and
Ruiqin Pan
[Abstract] [Full
Text Article]
Template Synthesis of Nanostructured
Carbonaceous Materials for Application in Electrochemical
Devices Pp. 506-513
Rocío Fernández-Saavedra, Pilar
Aranda, Kathleen A. Carrado, Giselle Sandí, Soenke
Seifert and Eduardo Ruiz-Hitzky
[Abstract] [Full
Text Article]
Distance in Zigzag Polyhex Nanotubes
Pp. 514-518
Mehdi Eliasi and Bijan Taeri
[Abstract] [Full
Text Article]
Formation of Nanoliter Droplets in a
Confined Microfluidic T-Shaped Junction: Formation Time and
Droplet Volume Pp. 519-526
Yuxiang Zhang, Jing Fan and Liqiu Wang
[Abstract] [Full
Text Article]
1+1>2: Extraordinary Fluid Conductivity
Enhancement Pp. 527-529
Xiaohao Wei and Liqiu Wang
[Abstract] [Full
Text Article]
Abstracts
[Back to top] [Full
Text Article]
Enhancement of Human Bone Marrow Cell Uptake of Quantum Dots
using Tat Peptide
Berry C.C., Harianawalw H., Loebus J., Oreffo R.O.C. and
de la Fuente J.
Nanotechnology is proving to play a major role in the
future of biomedical applications such as drug delivery, gene
therapy and cell imaging/tracking, in particular the use of
nanoparticles is regularly highlighted. However with regards
to nanoparticles, direct intracellular and intranuclear delivery
has, until recently, been difficult to achieve due to the
impermeable nature of the plasma and nuclear membranes. The
advent of cell penetrating peptides being employed as delivery
vectors has opened up many avenues with respect to targeted
delivery systems. In this paper, quantum dots were synthesised
and functionalised with the HIV-1 tat peptide, and uptake
into human bone marrow derived cell populations was assessed.
Results demonstrated an increase in uptake for tat modified
quantum dots, possibly via a different mechanism
to non-modified dots.
[Back to top]
[Full
Text Article]
State of the Art of Nanobiotechnology Applications in Neglected
Diseases
Nelson Durán, Priscyla D. Marcato, Zaine Teixeira,
Marcela Durán, Fabio T.M. Costa and
Marcelo Brocchi
The neglected diseases have not received any especial
public and private attention in the last years, as for example,
some parasitic diseases. Considerable amounts of private and
public money are needed to apply nanobiotechnology for the
treatment of neglected diseases. This review focuses on malaria,
leishmaniasis, schistosomiasis, trypanosomiasis, tuberculosis,
leprosy and filiarasis, and onchocerciasis where liposomes,
polymeric nanoparticles or nanostructured lipid carriers have
been applied. These nanocarrier systems have shown promissing
results in the treatment of many neglected diseases with diminished
toxicity and increased efficacy as well as a prolonged release
with a reduced number of dosages. Despite these promising
results, few nanocarriers have been used in clinical tests.
As far as we know, these references are a minority compared
to the number of studies of drug delivery systems that have
been published in the last years. Therefore, the challenge
for the researchers in this area is to generate interest amongst
the governments and industries for the treatment of neglected
diseases.
[Back to top]
[Full
Text Article]
Polymerosomes of PCL and PEG Demonstrate Enhanced Therapeutic
Efficacy of Insulin
Rachna Rastogi, Sneh Anand and
Veena Koul
The objective of the study was to evaluate the efficacy
of insulin loaded polymerosomes in diabetic rat model. To
achieve the purpose, amphiphilic triblock co-polymers of the
class poly(caprolactone)-poly(ethylene glycol) poly(caprolactone),
CEC were synthesized by ring-opening polymerization and characterized.
Polymerosomes were prepared by double emulsion method in the
size range of 75-130 nm at 25 °C as measured by differential
light scattering technique. Insulin was loaded in situ during
nanoparticle preparation. The release of insulin was observed
to be critically dependent on the caprolactone/ethylene glycol
ratio and particle size. The pharmacological activity ranged
from 22-36 h for various polymerosomes formulations in comparison
to poly(caprolactone), PCL nanoparticles which reached the
basal level after 4 h of administration. The polymerosomes
were therefore seen to enhance the insulin activity as well
as its stability in physiological fluid for a prolonged duration.
[Back to top]
[Full
Text Article]
Formulation of Nanosuspensions as a New Approach for
the Delivery of Poorly Soluble Drugs
Xiaohui Pu, Jin Sun, Mo Li and
Zhonggui He
Nanosuspensions have attracted much interest of many
scientists as a new approach to deliver poorly soluble drugs
because of their process flexibility and special advantages
such as improved oral bioavailability, high drug loading,
targeting capabilities and so on. Recently, the manufacture
processes of nanosuspensions have developed quickly, and some
new methods have emerged, for example, controlled precipitation,
emulsion method, microemulsion method and melt-emulsion method.
Additionally, the post-process of nanosuspension has also
gained great progresses to expand the utility of nanosuspensions,
including solidification technique and surface modification
technique. Moreover, the study on targeting delivery by nanosuspension
following intravenous administration has become a hot topic
of many researches. In the article, we will highlight new
developments in the production of nanosuspensions and summarize
the application of nanosuspensions via a variety of administration
routes. In the end, we will overview the research and development
prospectives of nanosuspensions.
[Back to top] [Full
Text Article]
Preparation and Characterization of Oil in Water Nano-Reservoir
Systems for Improved Oral Delivery of Atorvastatin
Gulam Mustafa, Zeenat I. Khan, Tripta Bansal
and Sushama Talegaonkar
The aim of present investigation was to develop novel
oil-in-water (o/w) nanoemulsion based formulation containing
atorvastatin for enhancing its oral bioavailability. Solubility
of atorvastatin in oil, surfactant and co surfactant was determined
to select the formulation ingredients. Pseudo ternary phase
diagrams were constructed by aqueous titration technique and
various nanoemulsion formulations were prepared. Formulations
taken from o/w nanoemulsion region were subjected to thermodynamic
stability and dispersibility tests in order to eliminate metastable
formulations in minimum possible time. In vitro drug release
was performed by dialysis bag method and compared with the
release of drug from suspension and conventional marketed
tablet. The optimized formulation showed higher drug release
(99.34%), lower droplet size (42.8 ± 0.42 nm), lower
polydispersity (0.237 ± 0.012), less viscosity (27.51
± 1.01 cP) and infinite dilution capability. A pharmacokinetic
study was performed after oral administration of atorvastatin
at 6 mg/kg in wistar rats. The area under the curve (AUC)
and maximum plasma concentration (Cmax)
in case of atorvastatin nanoemulsion were found 9-fold and
5-fold higher, respectively when compared to simple atorvastatin
suspension. The present study illustrated the potential of
nanoemulsion dosage form in improving biopharmaceutic performance
of atorvastatin.
[Back to top] [Full
Text Article]
Recent Advances in Nanoneurology for Drug Delivery to the
Brain
Jagat R. Kanwar, Ganesh Mahidhara and Rupinder
K. Kanwar
The drug development for neurodegenerative disorders
are the major challenge to the science in 21st
century. Many FDA approved drugs currently available in the
market have limitations in crossing the blood brain barrier
(BBB) owing to its complicated vasculature posed by the presence
of specialized cells. Nanotechnology is an emerging interdisciplinary
area, which have many applications including drug delivery.
Nanocarrier drug delivery involves targeting drugs enclosed
in a particular polymer and/or amphiphilic lipids. Controlled
release, nanoplatform availability for combinatorial therapy
and tissue specific targeting by using advanced technologies
such as molecular Trojan horse (MTH) technology are the promises
of nanotechnology. Different problems are associated with
drug delivery across the BBB. Some are mostly related to the
structure of brain microvasculature system while the others
are related to the nanomaterial structure. Different strategies,
such as using polymeric/solid lipid nanoparticles and surface
modification of nanomaterial with surfactants like polysorbates
have been conducted to solve these limitations. Also, nanodrug
formulations with double coatings have been designed for oral
delivery of drugs to overcome reticulo-endothelial system
and to improve their BBB permeability. It seems that the best
choice of strategy and material could be achieved with regard
to the physical and chemical structure of the drugs. The present
review discusses the potential applications of nanotechnology
for drug delivery across the BBB.
[Back to top] [Full
Text Article]
Two Novel Freeze-Dried pH-Sensitive Cyclosporine A Nanoparticles:
Preparation, in vitro Drug Release, and in vivo
Absorption Enhancement Effects
Fang Zhi-gang, Pan Ping, Yang Zhi-qiang, Chen
Ya-gen, Zhang Jian-kang, Wei Miao, Zhang Xue-nong and
Zhang Qiang
The present study was aimed at preparation and performance
evaluation of pH-sensitive cyclosporine A (CyA) nanoparticles
(CyA-NPs) to improve the poor bioavailability of lipophilic
CyA. CyA-NPs were prepared with two types of Eudragit®
copolymers (Eudragit®
S100 and Eudragit® L100)
by a quasi-emulsion solvent diffusion technique. Freeze-dried
formulations (Lac-CyA-S100-NP and Lac-CyA-L100-NP) were also
prepared. The physical properties, particle size, encapsulation
efficiency, and in vitro drug release characteristics
were studied. The in vivo bioavailability of CyA-NP
and Lac-CyA-S100-NP was investigated in rats at a dose of
15 mg/kg and compared with that of the commercial formulation,
Sandimmune Neoral®. The
mean particle size of the CyA NPs was less than 50 nm, and
the encapsulation efficiency was over 99%. Characteristics
of the freeze-dried nanoparticles were found to remain relatively
stable when lactose was used as a cryoprotectant. In vitro
release studies revealed that the CyA-NPs exhibited significant
pH-sensitivity. The relative bioavailabilities of CyA-L100-NP,
CyA-S100-NP, and Lac-CyA S100-NP were 117.3%, 162.1%, and
130.1%, respectively, when compared with that of Neoral®.
Therefore, CyA-NPs were considered to be promising oral delivery
systems for enhancement of the absorption of the poorly soluble
drug, CyA. Freeze-dried nanoparticles could be developed into
a novel and effective CyA formulations.
[Back to top] [Full
Text Article]
Self-Assembly from Low Dimension to Higher Conformation of
GGX Motif in Spider Silk Protein
Qinghan Zhou, Juan Lin, Feng Yuan, Zhaoyang Ye,
Feng Qiu, Chengkang Tang, Yongzhu Chen and Xiaojun
Zhao
Spider silk is intriguing because of its unique structure
and high performance mechanical properties. However, few studies
have presented data characterizing the conserved motifs found
in the silk protein as an oligopeptide. In this report a designed
peptide that mimics the repetitive GGX motif in the silk spidroin
was investigated. The peptide undergoes a ‘bottom-up’
self-assembly which was simply manipulated by metal ions and
an ionic self-complementary peptide, RADA16-I. In water, the
peptide was observed to form discrete and stiff nanorods (PNrs)
via hydrophobic interactions. AFM, TEM and DLS data showed
that the addition of MgCl2
or CaCl2 led to the formation
of a mass of nanorod bundles (PNrs-b). The addition of EDTA
forced the disruption of the bundles, therefore providing
evidence that the metal ions and peptide interact. Fourier
transform infrared spectroscopy showed the presence of coordination
bonds bridging the metal ions and the carbonyl groups of the
peptide. Such coordination bonds are considered to facilitate
the bundling of the nanorods. Conversely, mixing the GGX peptide
with the RADA16-I peptide caused a lengthening of the nanorods
(L-PNrs). Here, the length of the nanorods changed from several
microns to over ten microns. In addition, AFM was used to
follow the elongation process. Such a method provided a clear
and direct overview of the kinetics of self-assembly.
[Back to top] [Full
Text Article]
Nano-Mechanics and Membrane Receptor Mapping of CD8+
T Cells
Yangzhe Wu, Yi Hu, Hongsong Lu, Jiye Cai, Xianhui He and
Hongxia Zhao
The investigation of nano-mechanical properties and nano-architectures
of CD8+
T cells activated in vitro will help further interpret
the immune response/recognition of these cells at nanoscale
resolution. In this work, the local biophysical properties
of human peripheral blood CD8+
T cells were obtained, revealing the adhesion force of membrane
was increased after CD8+
T cells were stimulated with phorbol dibutyrate plus ionomycin,
though the measured local stiffness for resting and activated
cells was similar. The 3-D distribution pattern and grayscale
map together revealed that membrane receptors (CD8
and activation marker CD69)
distributed non-uniformly on the membrane and were shown as
micro-, nano-scale clusters or domains. This work describes
a relatively simple approach for exploiting the distribution
pattern of receptor molecules on a single T cell surface.
[Back to top]
[Full
Text Article]
A Convenient Synthesis Route to the Zinc Metagermanate Nanorods
L. Z. Pei, J. F. Wang, W. Tan, H. Y. Yu, C. G. Fan, J.
Chen and Qian-Feng Zhang
Zinc metagermanate nanorods have been synthesized by
a directly hydrothermal deposition process. The analyses of
X-ray diffraction (XRD) and high-resolution transmission electron
microscopy (HRTEM) indicate that the products are mainly composed
of ternary mixed oxide ZnGeO3
with multi-crystalline rhombohedral phase and porous structure.
The observation from scanning electron microscopy (SEM) and
transmission electron microscopy (TEM) shows that the nanorods
have a diameter of 100-600 nm and a length up to 30 µm.
Room temperature photoluminescence (PL) spectrum displays
that the nanorods have a strong emission band at a wavelength
of 400 nm. The proposed growth mechanism is also discussed
in the paper.
[Back to top]
[Full
Text Article]
A Surfactant-Free, Precursor-Induced Method to Flower-Like
ZnO Nanostructures
Lin Kong, Jia-Xiang Yang, Hong-Ping Zhou,
Yu-Peng Tian, Jie-Ying Wu and Bao-Kang Jin
Flower-like ZnO nanostructures had been successfully
synthesized by solvothermal treatment of a precursor 4,5-diphenyloxazole-2-propanoicacid-zinc
(abbreviated as oxaprozin-Zn) complex without using any surfactants.
The influence of basicity, temperature, and reaction time
on the formation of such structures was investigated. Room-temperature
photoluminescence spectrum of well-defined uniform ZnO nanoflowers
was investigated. The results indicated that the choice of
a precursor could have significant influence on the growth
of ZnO nanostructures. This type of complex could be used
to prepare other oxdinations with special morphology, suah
as CdO and CuO.
[Back to top]
[Full
Text Article]
ZnO Nanowires from Nanopillars: Influence of Growth Time
P. Sangpour, M. Roozbehi, O. Akhavan and A.Z.
Moshfegh
A double-tube vapor phase transport system has been used
to grow ZnO nanostructures. Nanopillars, nanorods and nanowires
of zinc oxide were synthesized on Au nanoparticle catalyst
depending on source-substrate distance and temperature gradient
in the quartz tube. In addition, influence of growth time
and substrate temperature on the morphology of the nanorods
and nanowires were also investigated. The scanning electron
microscope (SEM), X-ray diffraction (XRD) and transmission
electron microscopy (TEM) were employed to further understand
the nanostructures growth mechanism on various temperatures
and growth time steps. Longer length (>4µm) with
hexagonal-cross-sectional nanowires, in [002] growth orientation,
were synthesized at low temperatures (875 857°C); while
a middle length (<3µm) nanorods were formed at intermediate
temperatures (893-875°C). Nanopillars and other irregular
nanostructures were also synthesized on the surface at higher
temperatures (910-893°C). Based on the TEM observations,
the vapor–liquid–solid (VLS) growth mechanism
is applied to describe the growth processes for the synthesized
nanostructures.
[Back to top]
[Full
Text Article]
Microwave Rapid Synthesis of Nanoporous Fe3O4
Magnetic Microspheres
Da-Peng Yang, Feng Gao, Da-Xiang Cui and
Mo Yang
Nanoporous Fe3O4
magnetic microspheres have been successfully synthesized by
the way of microwave heating. The experimental process is
expeditious, simple and environmentally friendly. The obtained
sample is characterized by X-ray diffraction (XRD), transmission
electron microscopy (TEM), Brunauer-Emmett-Teller analysis
(BET), Fourier transform infrared (FT-IR), high-resolution
transmission electron microscopy (HRTEM) and magnetic measurements.
The average size of Fe3O4
microspheres is ~100nm and shows well-dispersed quality in
aqueous solution. More importantly, the microspheres possess
both nanoporous structure and superparamagnetic behaviour,
which endow them powerful application potentials in chemical,
biological/biomedical, physical and environmental engineering
fields, for example, catalyst or drug carrier, absorption,
separation and contrast agents, etc.
[Back to top]
[Full
Text Article]
Fabrication and Phase Transformation in Crystalline
Nanoparticles of PbZrO3 Derived
By Sol-Gel
Satyendra Singh and S.B. Krupanidhi
In this research fabrication of crystalline PbZrO3
(PZ) nanoparticles and their phase transformation
behavior is investigated. A novel sol-gel method was used
for the synthesis of air-stable and precipitate-free diol-based
sol of PZ, which was dried at 150 °C and then calcined
at 300-700°C for 1 h. The morphology, crystallinity and
phase formation of as synthesized nanoparticles were studied
by the selected-area electron diffraction (SAED), X-ray diffraction
(XRD), thermal gravimetric analysis/differential scanning
calorimetry (TGA-DSC), and high resolution transmission electron
microscope (HRTEM). The XRD, SAED, and TGA-DSC analyses confirmed
the tetragonal lead rich zirconia phase (t-Z phase) and monoclinic
zirconia phase (m-Z phase) as the intermediate phases during
the calcinations process followed by crystallization of single
orthorhombic PZ phase at about 700 oC. The average PZ particle
size was observed about 20 nm as confirmed by TEM study. Energy-dispersive
X-ray spectroscopy (EDX) analysis demonstrated that stoichiometric
PbZrO3 was
formed.
[Back to top]
[Full
Text Article]
Investigation on the Behaviour of Sputter-Deposited
Nanocrystalline Cr3Si Film
by Double Cathode Glow Discharge
Jiang Xu
In order to improve the wear resistance and oxidation
behaviors of Ti–6Al–4V alloy, the sputter-deposited
nanocrystalline Cr3Si film
was prepared on Ti–6Al–4V alloy substrate by double
cathode glow discharge. The nanocrystalline film was characterized
by using a variety of analytical techniques, such as XRD,
SEM, TEM, scratch tester, nanoindentation and Vickers microhardness
tester. The phase analysis results showed that the sputter-deposited
Cr3Si film (thickness 8µm)
was comprised of equiaxed nanocrystalline Cr3Si
with a grain size of less than 5 nm. The nanohardness of the
nanocrystalline Cr3Si was
2.37 times higher than that of coarse grained Cr3Si,
whereas the elastic modulus of nanocrystalline Cr3Si
was approaching to that of coarse-grained Cr3Si.
The critical load value obtained by scratch testing of the
nanocrystalline Cr3Si film
on Ti–6Al–4V alloy substrate was 80N, confirming
that the nanocrystalline Cr3Si
film was well adhered to Ti–6Al–4V alloy substrates.
Results of cyclic oxidation testing at 700°C and 800°C
in air showed that the oxidation kinetic curves of the nanocrystalline
Cr3Si film obeyed a parabolic
rate law, and oxide scale was mainly comprised of Cr2O3
and amorphous SiO2 with the
thickness of < 1µm that could effectively retard
the diffusion of oxygen into the nanocrystalline Cr3Si
film. The dry wear test results showed that specific wear
rate of nanocrystalline Cr3Si
film was two order magnitude smaller than that of Ti–6Al–4V
alloy at RT and 500°C.
[Back to top]
[Full
Text Article]
C20,
C24 and C26
Nanocrystal Series
Zhenxia Wang , Cuilan Ren, Zhenzhong Yong and
Ruiqin Pan
Small carbon nanocrystal particle (C20,
C24, C26)
series, synthesized in an ultrahigh molecular weight polyethylene
target by C2+ ion beam irradiation,
were studied with respect to their micro structures and sequential
growth features. As the samples were examined by laser desorption
Time-of-flight mass spectroscopy, relative intensive peaks
in the spectrum indicated the presence of C20,
C24, C26
carbon clusters. High resolution transmission electron microscopy
images and electron diffraction patterns showed that the C20,
C24, and C26
assembled into nanocrystal particles. Raman scattering spectrum
and Fourier transform infrared spectrum analyses also indicated
that the active bonds of small carbon cages were hydrogenated,
thus the C20, C24,
C26 nanocrystal were formed.
Additionally, the sequential growth of C20→C22→C24→C26→·
· ·
with addition of C2
carbon units was found, which provides a novel and efficient
approach to synthesize small hydro-fullerenes and their nanocrystal
materials.
[Back to top]
[Full
Text Article]
Template Synthesis of Nanostructured Carbonaceous Materials
for Application in Electrochemical Devices
Rocío Fernández-Saavedra, Pilar
Aranda, Kathleen A. Carrado, Giselle Sandí, Soenke
Seifert and Eduardo Ruiz-Hitzky
Novel conducting nanostructured carbonaceous materials
of various microstructures have been successfully prepared
from nanocomposites containing polyacrylonitrile (PAN) inside
the nanosized pores of imogolite, sepiolite and porous alumina
membrane templates. The synthesis and electrochemical characterization
of the PAN-inorganic porous solid nanocomposites, as well
as their carbonaceous derivatives produced after removal of
the matrix, have been studied by CHN elemental chemical analysis,
thermal analysis (TGDTA), specific surface area and porosity
determinations (N2 isotherms),
X-ray diffractometry, FTIR, Small-Angle X-ray Scattering (SAXS),
SEM, TEM and Electrochemical Impedance Spectroscopy (EIS).
The properties of the carbonaceous materials as electroactive
materials in electrochemical devices such as rechargeable
Li ion batteries and Electrochemical Double-Layer Capacitors
(EDLC) are reported. The main objective of this work is to
study the influence of the template used for the preparation
of different carbonaceous materials on their physical-chemical
characteristics as well as their electrochemical properties,
including their behaviour as electrode materials for Li-ion
batteries and EDLC capacitors.
[Back to top]
[Full
Text Article]
Distance in Zigzag Polyhex Nanotubes
Mehdi Eliasi and Bijan Taeri
Chemical compounds are often modeled as polygonal shapes,
where a vertex represents an atom and an edge symbolizes a
bond. Topological properties of molecular graphs of chemical
compounds can be correlated to their chemical properties and
biological activities. Topological indices are the oldest
and the most widely used to describing these activity relationships.
Many topological indices can be expressed in terms of the
distance concept in graphs. In this paper we explain a method,
using the concept of distance in the graphs of zigzag polyhex
nanotubes, which enables us to compute different topological
indices simultaneously.
[Back to top]
[Full
Text Article]
Formation of Nanoliter Droplets in a Confined Microfluidic
T-Shaped Junction: Formation Time and Droplet Volume
Yuxiang Zhang, Jing Fan and Liqiu Wang
Nanoliter droplet formation in a confined T-shaped junction
is analyzed in detail in virtue of an experimental visualization
system with a high speed camera. The movement of the back
interface of the tip of disperse phase penetrated into the
continuous phase plays an important role in determining droplet
formation time and droplet volume. A simple model of droplet
formation time based on the analysis of droplet formation
process is developed. Influences of continuous phase viscosity
and interfacial tension on droplet formation time and droplet
volume are concluded in terms of capillary number together
with the mean velocity of continuous phase. It is found that
both the capillary number and the flow rate ratio of disperse
phase to continuous phase have strong impacts on determining
droplet volume. Two empirical equations are derived from the
model for predicting droplet formation time and droplet volume,
respectively.
[Back to top]
[Full
Text Article]
1+1>2: Extraordinary Fluid Conductivity Enhancement
Xiaohao Wei and Liqiu Wang
We present the experimental evidence of substantial increases
in fluid thermal conductivity (up to 139%) by adding some
fluids even with lower conductivity. This leads to a new type
of thermal-wave fluids that could serve as heat transfer fluid
of the future much better than recently-proposed nanofluids.
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