7 research outputs found
Energy balance and global warming potential of corn straw-based bioethanol in China from a life cycle perspective
<p>As the second largest corn producer in this world, China has abundant corn straw resources. The study assessed the energy balance and global warming potential of corn straw-based bioethanol production and utilization in China from a life cycle perspective. The results revealed that bioethanol used as gasoline and diesel blend fuel could reduce global warming potential by 10%–97% and 4%–96%, respectively, as compared to gasoline and diesel for transport. The total global warming potential, net global warming potential, net energy, and Net Energy Ratio per MJ ethanol generated from corn straw-based bioethanol system are estimated to be 0.20 kg CO<sub>2</sub>-eq, 0.012 kg CO<sub>2</sub>-eq, 0.60 MJ, and 1.87, respectively. By using sensitivity analysis, we found that the collected coefficient and compressing density of straw have a more obvious influence on energy balance; transportation distance has a more obvious influence on global warming potential emission factor. The by-products may be utilized as fertilizer, animal feed, cement replacement, or high-value lignin chemicals, which make a contribution to offsetting 0.28 MJ per MJ ethanol of energy consumption.</p
What Governs Friction of Silicon Oxide in Humid Environment: Contact Area between Solids, Water Meniscus around the Contact, or Water Layer Structure?
In order to understand
the interfacial parameters governing the
friction force (<i>F</i><sub>t</sub>) between silicon oxide
surfaces in humid environment, the sliding speed (<i>v</i>) and relative humidity (RH) dependences of <i>F</i><sub>t</sub> were measured for a silica sphere (1 ÎĽm radius) sliding
on a silicon oxide (SiO<sub><i>x</i></sub>) surface, using
atomic force microscopy (AFM), and analyzed with a mathematical model
describing interfacial contacts under a dynamic condition. Generally, <i>F</i><sub>t</sub> decreases logarithmically with increasing <i>v</i> to a cutoff value below which its dependence on interfacial
chemistry and sliding condition is relatively weak. Above the cutoff
value, the logarithmic <i>v</i> dependence could be divided
into two regimes: (i) when RH is lower than 50%, <i>F</i><sub>t</sub> is a function of both <i>v</i> and RH; (ii)
in contrast, at RH ≥ 50%, <i>F</i><sub>t</sub> is
a function of <i>v</i> only, but not RH. These complicated <i>v</i> and RH dependences were hypothesized to originate from
the structure of the water layer adsorbed on the surface and the water
meniscus around the annulus of the contact area. This hypothesis was
tested by analyzing <i>F</i><sub>t</sub> as a function of
the water meniscus area (<i>A</i><sub>m</sub>) and volume
(<i>V</i><sub>m</sub>) estimated from a thermally activated
water-bridge formation model. Surprisingly, it was found that <i>F</i><sub>t</sub> varies linearly with <i>V</i><sub>m</sub> and correlates poorly with <i>A</i><sub>m</sub> at RH < 50%; and then its <i>V</i><sub>m</sub> dependence
becomes weaker as RH increases above 50%. Comparing the friction data
with the attenuated total reflection infrared (ATR-IR) spectroscopy
analysis result of the adsorbed water layer, it appeared that the
solidlike water layer structure formed on the silica surface plays
a critical role in friction at RH < 50% and its contribution diminishes
at RH ≥ 50%. These findings give a deeper insight into the
role of water condensation in friction of the silicon oxide single
asperity contact under ambient conditions
Fabrication of a Homogeneous, Integrated, and Compact Film of Organic–Inorganic Hybrid Ni(en)<sub>3</sub>Ag<sub>2</sub>I<sub>4</sub> with Near-Infrared Absorbance and Semiconducting Features
The organic–inorganic hybrid
crystal NiÂ(en)<sub>3</sub>Ag<sub>2</sub>I<sub>4</sub> (where en represents
1,2-ethylenediamine) crystallizes in hexagonal space group <i>P</i>6<sub>3</sub>, in which the AgI<sub>4</sub><sup>3–</sup> tetrahedra connect into a diamondlike inorganic framework via sharing
of the vertex and the NiÂ(en)<sub>3</sub><sup>2+</sup> octahedra fill
in the pores of the framework. UV–vis–near-IR (NIR)
spectroscopy disclosed that this hybrid shows intense NIR absorbance
centered at ca. 870 nm, and the variable-temperature conductivity
measurement revealed that the hybrid is a semiconductor with <i>E</i><sub>a</sub> = 0.46 eV. The electronic band structure of
NiÂ(en)<sub>3</sub>Ag<sub>2</sub>I<sub>4</sub> was calculated using
the density functional theory method, indicating that the NIR absorbance
arises from d-d transition within the Ni<sup>2+</sup> cation of NiÂ(en)<sub>3</sub><sup>2+</sup>. The homogeneous, compact, and transparent crystalline
film of NiÂ(en)<sub>3</sub>Ag<sub>2</sub>I<sub>4</sub> was fabricated
via a secondary seed growth strategy, which has promising application
in NIR devices
Graphene Failure under MPa: Nanowear of Step Edges Initiated by Interfacial Mechanochemical Reactions
The
low wear resistance of macroscale graphene coatings does not
match the ultrahigh mechanical strength and chemical inertness of
the graphene layer itself; however, the wear mechanism responsible
for this issue at low mechanical stress is still unclear. Here, we
demonstrate that the susceptibility of the graphene monolayer to wear
at its atomic step edges is governed by the mechanochemistry of frictional
interfaces. The mechanochemical reactions activated by chemically
active SiO2 microspheres result in atomic attrition rather
than mechanical damage such as surface fracture and folding by chemically
inert diamond tools. Correspondingly, the threshold contact stress
for graphene edge wear decreases more than 30 times to the MPa level,
and mechanochemical wear can be described well with the mechanically
assisted Arrhenius-type kinetic model, i.e., exponential dependence
of the removal rate on the contact stress. These findings provide
a strategy for improving the antiwear of graphene-based materials
by reducing the mechanochemical interactions at tribological interfaces
Data_Sheet_1_The improvement of Hovenia acerba-sorghum co-fermentation in terms of microbial diversity, functional ingredients, and volatile flavor components during Baijiu fermentation.pdf
The quality of Baijiu was largely affected by raw materials, which determine the flavor and taste. In the present study, organic acids, polyphenols, volatile flavor components and microbial community in Hovenia acerba-sorghum co-fermented Baijiu (JP1) and pure sorghum-fermented Baijiu (JP2) were comprehensively analyzed. Organic acids, polyphenols and volatile flavor components in JP1 were more abundant than JP2. The abundance and diversity of bacteria and fungi in JP1 was higher than that in JP2 in the early stage of fermentation, but presented opposite trend in the middle and late stages. Leuconostoc, Lentilactobacillus and Issatchenkia were dominant genera in JP1. Whereas, Cronobacter, Pediococcus and Saccharomyces occupied the main position in JP2. Lentilactobacillus and Issatchenkia were positively related to most of organic acids and polyphenols. Pseudomonas, Rhodococcus, Cronobacter, Pediococcus, Brucella, Lentilactobacillus, Lactobacillus, Saccharomycopsis, Wickerhamomyces, Aspergillus, Thermomyces and unclassified_f—Dipodascaccae were associated with the main volatile flavor components. The main metabolic pathways in two JPs exhibited the variation trend of first decreasing and then increasing, and the metabolism activity in JP1 were higher than that in JP2. The results demonstrated the introduction of Hovenia acerba improved the functional ingredients and volatile flavor components, which is helpful for the quality promotion of Baijiu. This study identified the key microorganisms and discussed their effect on organic acids, polyphenols and volatile flavor components during the fermentation of Baijiu with different raw materials, providing a scientific basis for the development and production of high-quality Baijiu.</p
Nanocolloidosomes with Selective Drug Release for Active Tumor-Targeted Imaging-Guided Photothermal/Chemo Combination Therapy
Selective drug release
is highly desirable for photothermal/chemo combination therapy when
two or even more theranostic agents are encapsulated together within
the same nanocarrier. A conventional nanocarrier can hardly achieve
this goal. Herein, doxorubicin and indocyanine green (DOX/ICG)-loaded
nanocolloidosomes (NCs), with selective drug release, were fabricated
as a novel multifunctional theranostic nanoplatform for photothermal/chemo
combination therapy. Templating from galactose-functionalized hydroxyethyl
starch-polycaprolactone (Gal-HES-PCL) nanoparticles-stabilized Pickering
emulsions, the resultant DOX/ICG@Gal-HES-PCL NCs had a diameter of
around 140 nm and showed an outstanding tumor-targeting ability, preferable
tumor penetration capability, and promotion of photothermal effect.
Moreover, these NCs can be used for NIR fluorescence imaging and thus
render real-time imaging of solid tumors with high contrast. Collectively,
such NCs achieved the best in vivo antitumor efficacy combined with
laser irradiation compared with DOX/ICG@HES-PCL NCs and DOX/ICG mixture.
These NCs are valuable for active tumor-targeted imaging-guided combination
therapy against liver cancer and potentially other diseases
α‑Amylase- and Redox-Responsive Nanoparticles for Tumor-Targeted Drug Delivery
Paclitaxel (PTX)
is an effective antineoplastic agent and shows potent antitumor activity
against a wide spectrum of cancers. Yet, the wide clinical use of
PTX is limited by its poor aqueous solubility and the side effects
associated with its current therapeutic formulation. To tackle these
obstacles, we report, for the first time, α-amylase- and redox-responsive
nanoparticles based on hydroxyethyl starch (HES) for the tumor-targeted
delivery of PTX. PTX is conjugated onto HES by a redox-sensitive disulfide
bond to form HES–SS-PTX, which was confirmed by results from
NMR, high-performance liquid chromatography-mass spectrometry, and
Fourier transform infrared spectrometry. The HES–SS-PTX conjugates
assemble into stable and monodispersed nanoparticles (NPs), as characterized
with Dynamic light scattering, transmission electron microscopy, and
atomic force microscopy. In blood, α-amylase will degrade the
HES shell and thus decrease the size of the HES–SS-PTX NPs,
facilitating NP extravasation and penetration into the tumor. A pharmacokinetic
study demonstrated that the HES–SS-PTX NPs have a longer half-life
than that of the commercial PTX formulation (Taxol). As a consequence,
HES–SS-PTX NPs accumulate more in the tumor compared with the
extent of Taxol, as shown in an in vivo imaging study. Under reductive
conditions, the HES–SS-PTX NPs could disassemble quickly as
evidenced by their triggered collapse, burst drug release, and enhanced
cytotoxicity against 4T1 tumor cells in the presence of a reducing
agent. Collectively, the HES–SS-PTX NPs show improved in vivo
antitumor efficacy (63.6 vs 52.4%) and reduced toxicity in 4T1 tumor-bearing
mice compared with those of Taxol. These results highlight the advantages
of HES-based α-amylase- and redox-responsive NPs, showing their
great clinical translation potential for cancer chemotherapy