44 research outputs found
Photoconversion of Chlorinated Saline Wastewater DBPs in Receiving Seawater is Overall a Detoxification Process
Chlorine disinfection of wastewater
effluents rich in bromide and
iodide ions results in the formation of relatively toxic bromo- and
iodo-disinfection byproducts (DBPs), especially highly toxic bromophenolic
and iodophenolic DBPs, which could harm the marine ecosystem when
they are discharged into receiving seawater along with the wastewater
effluents. In this study, we investigated the conversion of three
individual halophenolic DBPs (5-bromosalicylic acid, 2,5-dibromohydroquinone,
and 2,4,6-triiodophenol) and two chlorinated saline wastewater DBP
mixtures in seawater. The conversion products were analyzed with ultra
performance liquid chromatography/electrospray ionization-triple quadrupole
mass spectrometry, and the conversion of overall halo-DBPs in the
wastewater DBP mixtures was monitored by measuring total organic halogen.
The photoconversion-induced variations in the toxicity were evaluated
using the embryos of a marine polychaete. Halophenolic DBPs were found
to undergo photoconversion in seawater. The conversion was triggered
by photonucleophilic substitution: bromophenolic and iodophenolic
DBPs were converted to their chlorophenolic or hydroxyphenolic analogues,
via substituting the bromine and iodine atoms with chloride or hydroxide
ions in seawater; chlorophenolic DBPs were converted to their hydroxyphenolic
analogues, via substituting the chlorine atoms with hydroxide ions
in seawater. The hydroxyphenolic analogues thus formed further decomposed
and finally cleaved to aliphatic compounds. The photoconversion of
chlorinated saline wastewater DBPs in receiving seawater was overall
a dehalogenation and detoxification process
Comparative Toxicity of Chlorinated Saline and Freshwater Wastewater Effluents to Marine Organisms
Toilet
flushing with seawater results in saline wastewater, which
may contain approximately 33–50% seawater. Halogenated disinfection
byproducts (DBPs), especially brominated and iodinated DBPs, have
recently been found in chlorinated saline wastewater effluents. With
the occurrence of brominated and iodinated DBPs, the adverse effects
of chlorinated saline wastewater effluents to marine ecology have
been uncertain. By evaluating the developmental effects in the marine
polychaete <i>Platynereis dumerilii</i> directly exposed
to chlorinated saline/freshwater wastewater effluents, we found surprisingly
that chlorinated saline wastewater effluents were less toxic than
a chlorinated freshwater wastewater effluent. This was also witnessed
by the marine alga <i>Tetraselmis marina</i>. The toxicity
of a chlorinated wastewater effluent to the marine species was dominated
by its relatively low salinity compared to the salinity in seawater.
The organic matter content in a chlorinated wastewater effluent might
be partially responsible for the toxicity. The adverse effects of
halogenated DBPs on the marine species were observed pronouncedly
only in the “concentrated” chlorinated wastewater effluents.
pH and ammonia content in a wastewater effluent caused no adverse
effects on the marine species. The results suggest that using seawater
to replace freshwater for toilet flushing might mitigate the “direct”
acute detrimental effect of wastewater to the marine organisms
Demand-side Regulation Provision of Virtual Power Plants Consisting of Interconnected Microgrids through Double-stage Double-layer Optimization
Demand-side Regulation Provision of Virtual Power Plants Consisting of Interconnected Microgrids through Double-stage Double-layer Optimizatio
Formation of Brominated Disinfection Byproducts during Chloramination of Drinking Water: New Polar Species and Overall Kinetics
The
formation of brominated disinfection byproducts (Br-DBPs),
which are generally significantly more cytotoxic and genotoxic than
their chlorinated analogues, in chloramination has not been fully
examined. In this work, the formation of new polar Br-DBPs in simulated
drinking waters was examined using state-of-the-art ultraperformance
liquid chromatography/electrospray ionization-triple quadrupole mass
spectrometry. As many as 29 aliphatic, aromatic, or nitrogenous polar
Br-DBPs were detected in chloramination, and five of them (including
2,4,6-tribromoresorcinol, 2,6-dibromo-4-nitrophenol, 2,2,4-tribromo-5-hydroxy-4-cyclopentene-1,3-dione,
2,2,4-dibromochloro-5-hydroxy-4-cyclopentene-1,3-dione, and 2,2,4-bromodichloro-5-hydroxy-4-cyclopentene-1,3-dione)
were tentatively identified. Unlike chlorination, chloramination favored
the formation of aromatic and nitrogenous polar Br-DBPs and was mild
enough to allow polar intermediate Br-DBPs to accumulate. To further
explore the formation mechanism of Br-DBPs in chloramination, a quantitative
empirical model involving 33 major reactions was developed to describe
the overall kinetics. According to the modeling results, bromochloramine
and monobromamine were the major species responsible for 54.2–58.1%
and 41.7–45.7%, respectively, of the formed Br-DBPs, while
hypobromous acid accounted for only 0.2% of the formed Br-DBPs; direct
reactions between monochloramine and natural organic matter accounted
for the majority of the formed chlorinated DBPs (93.7–95.1%);
hypochlorous acid and hypobromous acid in the chloramination were
at ng/L or subng/L levels, which were not enough to cause polar intermediate
Br-DBPs to decompose
Liquid Crystalline Behavior of Graphene Oxide in the Formation and Deformation of Tough Nanocomposite Hydrogels
In this paper, we report the formation
and transformation of graphene
oxide (GO) liquid crystalline (LC) structures in the synthesis and
deformation of tough GO nanocomposite hydrogels. GO aqueous dispersions
form a nematic LC phase, while the addition of polyÂ(<i>N</i>-vinylpyrrolidone) (PVP) and acrylamide (AAm), which are capable
of forming hydrogen bonding with GO nanosheets, shifts the isotropic/nematic
transition to a lower volume fraction of GO and enhances the formation
of nematic droplets. During the gelation process, a phase separation
of the polymers and GO nanosheets is accompanied by the directional
assembly of GO nanosheets, forming large LC tactoids with a radial
GO configuration. The shape of the large tactoids evolves from a sphere
to a toroid as the tactoids increase in size. Interestingly, during
cyclic uniaxial tensile deformation a reversible LC transition is
observed in the very tough hydrogels. The isolated birefringent domains
and the LC domains in the tactoids in the gels are highly oriented
under a high tensile strain
Synthesis of Graphene Peroxide and Its Application in Fabricating Super Extensible and Highly Resilient Nanocomposite Hydrogels
Functionalized graphene has been considered as one of the most important materials for preparing polymer nanocomposites due to its unique physical structure and properties. To increase the interfacial interaction between polymer component and graphene oxide (GO) sheets, <i>in situ</i> grafting polymerization initiated by a free radical initiator immobilized on GO sheets is a better choice. We report a facile and effective strategy for preparing graphene peroxide (GPO) <i>via</i> the radiation-induced peroxidation of GO. The formation of peroxides on GO is proven by iodometric measurement and other characterizations. Using GPO as a polyfunctional initiating and cross-linking center, we obtained GO composite hydrogels exhibiting excellent mechanical properties, namely, very high tensile strength (0.2–1.2 MPa), extremely high elongations (2000–5300%), and excellent resilience. This work provides new insight into the fabrication of GO/polymer nanocomposites to fulfill the excellent mechanical properties of graphene
sj-docx-1-hol-10.1177_09596836231197769 – Supplemental material for Holocene summer temperature record based on branched tetraethers in Northeast China
Supplemental material, sj-docx-1-hol-10.1177_09596836231197769 for Holocene summer temperature record based on branched tetraethers in Northeast China by Zeyang Zhu, Jing Wu, Jiaxin Lu, Guoqiang Chu, Patrick Rioual, Luo Wang and Jiaqi Liu in The Holocene</p
Integrating a Biomineralized Nanocluster for H<sub>2</sub>S‑Sensitized ROS Bomb against Breast Cancer
Nanomaterial-assisted
chemodynamic therapy (CDT) has received considerable
attention in recent years. It outperforms other modalities by its
distinctive reactive oxygen species (ROS) generation through a nonexogenous
stimulant. However, CDT is limited by the insufficient content of
endogenous hydrogen peroxide (H2O2). Herein,
a biodegradable MnS@HA-DOX nanocluster (MnS@HA-DOX NC) was constructed
by in situ biomineralization from hyaluronic acid,
to enlarge the ROS cascade and boost Mn2+-based CDT. The
acid-responsive NCs could quickly degrade after internalization into
endo/lysosomes, releasing Mn2+, H2S gas, and
anticancer drug doxorubicin (DOX). The Fenton-like reaction catalyzed
by Mn2+ was amplified by both H2S and DOX, producing
a mass of cytotoxic ·OH radicals. Through the combined action
of gas therapy (GT), CDT, and chemotherapy, oxidative stress would
be synergistically enhanced, inducing irreversible DNA damage and
cell cycle arrest, eventually resulting in cancer cell apoptosis
MOESM3 of Both HDAC5 and HDAC6 are required for the proliferation and metastasis of melanoma cells
Additional file 3: Figure S3. Knocking down HDAC6 induced apoptosis with time course. Annexin V was used to stain the apoptotic cells and PI was used to stain the dead cells. After constructing knocking down HDAC6 stable cells, we continued to culture these cells in RPMI1640 medium and collected cells with a time course: 1, 3, 5 and 7Ă‚Â days
MOESM2 of Both HDAC5 and HDAC6 are required for the proliferation and metastasis of melanoma cells
Additional file 2: Figure S2. Screening for an efficient shRNA for HDAC5 or HDAC6 knockdown. The seq used for RNA interference are listed in Materials and Methods. HDAC5 (or HADC6) shRNA vectors were transiently transfected in HEK293T cells, and the cells were collected 36 h later, washed twice with ice cold PBS, and centrifuged at 1000 rpm for 5 min. Then, 1 × SDS loading buffer was added and boiled for 10 min; then 10 μl of samples was loaded for SDS-PAGE. β-actin was used as an internal control