Small Volume Variation Research Articles

Carbon coated and oxygen vacancies incorporated Wadsley-Roth phase molybdenum niobium oxide for high-performance lithium-ion storage

Nb-based oxides with Wadsley-Roth shear structure have been aroused extensive research interest as promising anode for Li-ion batteries, due to the multi-electron redox, safe working voltage and open structural framework. However, the low intrinsic electronic conductivity limits their further practical applications. Herein, the lithium storage performances of MoNb6O18 with Wadsley-Roth shear structure are optimized by carbon coating and oxygen vacancies (VO-MNO@C), which synthesized with freeze-drying and subsequently heat treatment. As expected, the VO-MNO@C electrode demonstrates a high initial reversible capacity of 259.6 mAh/g at 0.2C and the capacity retention rate of 85.7 % after 200 cycles at 1C. Moreover, the reversible of Mo6+/Mo5+ and Mo5+/Mo4+ redox reaction can be effectively improved. In situ X-ray diffraction (XRD) and ex situ X-ray photoelectron spectroscopy (XPS) characterization indicate that VO-MNO@C undergoes a solid-solution structural evolution disclosing the stepwise reaction of Mo5+/Mo6+, Mo4+/Mo5+, Nb4+/Nb5+ and Nb3+/Nb4+ redox couples with a small volume variation of 5.7 %. Also, the full cell based on commercial LiMn2O4 cathode and VO-MNO@C anode displays an operating voltage about 2.4 V with the high energy density of 681.4 Wh/kg (calculated with the mass of anode). This work will offer more insights for the development of Wadsley-Roth shear structure anode materials with excellent Li-ion storage properties.

Reduced Volume Expansion of Micron-Sized SiOx via Closed-Nanopore Structure Constructed by Mg-Induced Elemental Segregation.

The inherently huge volume expansion during Li uptake has hindered the use of Si-based anodes in high-energy lithium-ion batteries. While some pore-forming and nano-architecting strategies show promises to effectively buffer the volume change, other parameters essential for practical electrode fabrication, such as compaction density, are often compromised. Here we propose a new in situ Mg doping strategy to form closed-nanopore structure into a micron-sized SiOx particle at a high bulk density. The doped Mg atoms promote the segregation of O, so that high-density magnesium silicates form to generate closed nanopores. By altering the mass content of Mg dopant, the average radii (ranged from 5.4 to 9.7 nm) and porosities (ranged from 1.4 % to 15.9 %) of the closed pores are precisely adjustable, which accounts for volume expansion of SiOx from 77.8 % to 22.2 % at the minimum. Benefited from the small volume variation, the Mg-doped micron-SiOx anode demonstrates improved Li storage performance towards realization of a 700-(dis)charge-cycle, 11-Ah-pouch-type cell at a capacity retention of >80 %. This work offers insights into reasonable design of the internal structure of micron-sized SiOx and other materials that undergo conversion or alloying reactions with drastic volume change, to enable high-energy batteries with stable electrochemistry.

Reduced Volume Expansion of Micron‐Sized SiOx via Closed‐Nanopore Structure Constructed by Mg‐Induced Elemental Segregation

AbstractThe inherently huge volume expansion during Li uptake has hindered the use of Si‐based anodes in high‐energy lithium‐ion batteries. While some pore‐forming and nano‐architecting strategies show promises to effectively buffer the volume change, other parameters essential for practical electrode fabrication, such as compaction density, are often compromised. Here we propose a new in situ Mg doping strategy to form closed‐nanopore structure into a micron‐sized SiOx particle at a high bulk density. The doped Mg atoms promote the segregation of O, so that high‐density magnesium silicates form to generate closed nanopores. By altering the mass content of Mg dopant, the average radii (ranged from 5.4 to 9.7 nm) and porosities (ranged from 1.4 % to 15.9 %) of the closed pores are precisely adjustable, which accounts for volume expansion of SiOx from 77.8 % to 22.2 % at the minimum. Benefited from the small volume variation, the Mg‐doped micron‐SiOx anode demonstrates improved Li storage performance towards realization of a 700‐(dis)charge‐cycle, 11‐Ah‐pouch‐type cell at a capacity retention of >80 %. This work offers insights into reasonable design of the internal structure of micron‐sized SiOx and other materials that undergo conversion or alloying reactions with drastic volume change, to enable high‐energy batteries with stable electrochemistry.

Double-pinning effect assisting Na4VMn(PO4)3 with superior structural and electrochemical stabilization for sodium-ion batteries

The Na superionic conductor of (NASICON)-type Na4VMn(PO4)3 (NVMP) with a three-dimensional framework and high operating voltage has been extensively investigated for sodium-ion batteries (SIBs). However, unexpected Jahn-Teller effect and sluggish Na+ diffusion kinetics inevitably lead to rapid capacity fade and unfavorable structural distortion. Herein, the double-pinning effect of Al/F co-doping was adopted for the NVMP system to enhance structural stability and facilitate Na+ diffusion. The as-synthesized NVMP-Al&F presents a highly reversible capacity of 110 mAh g−1 at 0.1 C, accompanied with a long-term lifespan of 1000 cycles at 5 C (capacity retention of 86.1 %). Moreover, in situ X-ray diffraction affirms the reversible structural evolution and small volume variation (∼4.43 %) during the highly reversible sodiation/desodiation processes. Benefiting from the double-pinning effect, the lowered Na+ migration barrier effectively facilitates Na+ diffusion and increases to higher reversible capacity by combining theoretical calculation and kinetic analysis. The assembled NVMP-Al&F//hard carbon (HC) full cell manifests a high energy density of 353.9 Wh kg−1 and excellent cycling durability of 91.3 % at 1 C after 100 cycles. This work sheds light on the double-pinning as a novel strategy to boost the cycling stability of high-performance NASICON-type cathodes.

Whole-Voltage-Range Solid-Solution Reaction in Layered Oxide Cathode of Sodium-Ion Batteries.

Layered manganese-based oxides (LMOs) are promising cathode materials for sodium-ion batteries (SIBs) due to their versatile structures. However, the Jahn-Teller effect of Mn3+ induces severe distortion of MnO6 octahedra, and the resultant low symmetry is responsible for the gliding of MnO2 layers and then inferior multiple-phase transitions upon Na+ extraction/insertion. Here, hexagonal P2-Na0.643 Li0.078 Mn0.827 Ti0.095 O2 is synthesized through the incorporation of Li and Ti into the distorted orthorhombic P'2-Na0.67 MnO2 to function as a phase-transition-free oxide cathode. It is revealed that Li in both the transition-metal and Na layers enhances the covalency of Mn-O bonds and allows degeneracy of Mn 3d eg orbitals to favor the formation of hexagonal phase, and the high strength of Ti-O bonds reduces the electrostatic interaction between Na and O for suppressed Na+ /vacancy rearrangements. These collectively lead to a whole-voltage-range solid-solution reaction between 1.8 and 4.3V with a small volume variation of 1.49%. This rewards its excellent cycling stability (capacity retention of 90% after 500 cycles) and rate capability (89 mAh g-1 at 2000mA g-1 ).

Compressibility Effect on Darcy Porous Convection

Perfectly incompressible materials do not exist in nature but are a useful approximation of several media which can be deformed in non-isothermal processes but undergo very small volume variations. In this paper, the linear analysis of the Darcy-Bénard problem is performed in the class of extended-quasi-thermal-incompressible fluids, introducing a factor beta which describes the compressibility of the fluid and plays an essential role in the instability results. In particular, in the Oberbeck-Boussinesq approximation, a more realistic constitutive equation for the fluid density is employed in order to obtain more thermodynamically consistent instability results. The critical Rayleigh-Darcy number for the onset of convection is determined, via linear instability analysis of the conduction solution, as a function of a dimensionless parameter widehat{beta } proportional to the compressibility factor beta, proving that widehat{beta } enhances the onset of convective motions.Article HighlightsThe onset of convection in fluid-saturated porous media is analyzed, taking into account fluid compressibility effect.The critical Rayleigh-Darcy number is determined in a closed algebraic form via linear instability analysis.The critical Rayleigh-Darcy number is shown to be a decreasing function of the dimensionless compressibility factor.

Low-content SnO2 nanodots on N-doped graphene: lattice-confinement preparation and high-performance lithium/sodium storage.

Rational construction of nanosized anode nanomaterials is crucial to enhance the electrochemical performance of lithium-/sodium-ion batteries (LIBs/SIBs). Various anode nanoparticles are created mainly via templating surface confinement, or encapsulation within precursors (such as metal-organic frameworks). Herein, low-content SnO2 nanodots on N-doped reduced graphene oxide (SnO2@N-rGO) were prepared as anode nanomaterials for LIBs and SIBs, via a distinctive lattice confinement of a CoAlSn-layered double hydroxide (CoAlSn-LDH) precursor. The SnO2@N-rGO composite exhibits the advantagous features of low-content (17.9 wt%) and uniform SnO2 nanodots (3.0 ± 0.5 nm) resulting from the lattice confinement of the Co and Al species to the surrounded Sn within the same crystalline layer, and high-content conductive rGO. The SnO2@N-rGO composite delivers a highly reversible capacity of 1146.2 mA h g-1 after 100 cycles at 0.1 A g-1 for LIBs, and 387 mA h g-1 after 100 cycles at 0.1 A g-1 for SIBs, outperforming N-rGO. Furthermore, the dominant capacitive contribution and the rapid electronic and ionic transfer, as well as small volume variation, all give rise to the enhancement. Precursor-based lattice confinement could thus be an effective strategy for designing and preparing uniform nanodots as anode nanomaterials for electrochemical energy storage.

In-situ fabrication of Si/FeSi2@C NPs with volume control effect by fluidized bed chemical vapor deposition as anode materials

Silicon (Si) has been proven to be the most potential anode material for the next-generation lithium-ion batteries (LIBs) because of its superior theoretical capacity (∼4200 mAh g−1). However, the huge volume changes, unstable solid-state interphase (SEI) layers, and large internal stresses upon the lithiation process severely limit the practical application for commercial LIBs anodes. Herein, we fabricate the carbon-coated Si/FeSi2 nanoparticles (Si/FeSi2 @C NPs) with volume control effect by fluidized bed chemical vapor deposition (FBCVD) method to solve the above-mentioned problems. These 15 min-Si/FeSi2 @C NPs and 30 min-Si/FeSi2 @C NPs show excellent Li+ storage capacity in the first cycle (2705.9/3039.1 mAh g-1 and 2645.9/2984.2 mAh g-1) with high Initial Coulombic Efficiency (ICE) of ∼89.0% and 88.7%. In-situ TEM characterization demonstrates that the carbon coating layer and inert FeSi2 phase enable a small volume variation, only ∼37.8%, revealing the effective volume expansion control effect, and generating thin SEI layers. Besides, the perfect structure of Si/FeSi2 @C NPs makes this material a great improvement in rate performance.

Fluffy-Like Cation-Exchanged Prussian Blue Analogues for Sodium-Ion Battery Cathodes.

Prussian blue (PB) and its analogues are considered as promising cathode materials for sodium-ion batteries (SIBs) owing to their low cost and high capacity. However, it is still a huge challenge to avoid obvious capacity decay during cycling due to the structural collapse. Herein, we design a method to replace parts of Fe ion sites in PB with Ni ions to prepare fluffy-like nickel PB (PB-Ni) by cationic solution immersion, which improves cycling stability for sodium storage. The content of Ni in PB-Ni is explored by regulating the soaking time in the Ni-containing solution, which results in different effects on the electrochemical performance as cathodes of SIBs. Especially, PB-Ni-1d (soaking in NiCl2 solution for 1 day) exhibits an initial capacity of 114.2 mA h g-1 at 50 mA g-1 and a stable cycling performance of 800 cycles at 300 mA g-1. Furthermore, the reversible phase transformation and small volume variation for PB-Ni-1d are revealed by in situ X-ray diffraction characterization. The nickel hexacyanoferrate in outer layer maintains the cubic phase to stabilize the crystal structure. The cation-exchange strategy provides a facile idea to fabricate high-quality PB cathodes with superior stability for high-performance SIBs.

Low-cost layered oxide cathode involving cationic and anionic redox with a complete solid-solution sodium-storage behavior

Iron/manganese-based layered transition-metal oxides have attracted numerous attentions as promising cathodes for sodium-ion batteries (SIBs) due to their high theoretical capacities and abundant reserves, yet they still suffer from detrimental phase transitions and fast capacity fading. Herein, we realize a complete solid-solution sodiation/desodiation behavior over a wide voltage range of 1.5–4.3 V in a novel P2-Na0.75Ca0.05Li0.15Fe0.2Mn0.6O2 (P2-NCLFMO) cathode material, where cationic and anionic redox reactions synergistically provide charge compensation. Li ions in transition-metal (TM) sites not only trigger the oxygen redox activity, but also increase the Na content for stabilizing the P2-structure at high voltage and weaken the Jahn-Teller effect by diluting the Mn3+ concentration; Ca ions in Na sites serve as “pillars” to stabilize the layered structure and alleviate the lattice oxygen release. The complete solid-solution reaction in the wide voltage range ensures both rapid Na+ diffusivity and small volume variation. Therefore, the P2-NCLFMO cathode shows outstanding rate capability (183 mAh g−1 at 0.1C in comparison with 49.9 mAh g−1 at 20C) and respectable cycling performance (76% capacity retention after 150 cycles at 1C). Additionally, the prototype Na-ion full battery constructed by the P2-NCLFMO cathode and hard carbon anode delivers a promising energy density of 246.3 Wh kg−1. This work provides a new platform for achieving high-energy and long-life layered oxide cathodes involving cationic and anionic redox by eliminating the irreversible phase transitions.

Sulfurized Polyacrylonitrile as a High-Performance and Low-Volume Change Anode for Robust Potassium Storage.

Potassium-ion batteries (KIBs) are considered as low-cost electrochemical energy storage technologies because of the abundant potassium resources. However, the practical applications of KIBs are mainly hampered by the unsatisfactory electrochemical performance of anode materials which often undergo large volume variations during potassiation-depotassiation, limiting their cycling life. Here, low-cost sulfurized polyacrylonitrile (S-PAN) is reported as an attractive anode candidate for KIBs. It provides a high potassium storage capacity of 569 mAh g(S-PAN)-1 with decent rate capability and cycling stability (no capacity loss after 1500 cycles, running time ∼188 days). Detailed ex situ spectroscopic and in situ microscopic characterizations reveal that the distinguished electrochemical performance of S-PAN is attributed to the high reversibility of its covalent C-S and S-S bonds which undergo repeated cleavage-redimerization during potassiation-depotassiation concomitant with relatively small volume variation (less than 24.2%). Subsequently, a full-cell constructed by pairing high-voltage K2MnFe(CN)6 cathode with high-capacity S-PAN anode demonstrates an attractive energy density (290.9 Wh kg-1) and long-term cycling stability (1200 cycles with 95.4% capacity retention). Given the high performance and low cost of both anode and cathode materials, it is believed that the present full-cell promises it as a competitive energy storage system for the cost-sensitive grid-scale applications.

Machine Learning Screening of Metal-Ion Battery Electrode Materials.

Rechargeable batteries provide crucial energy storage systems for renewable energy sources, as well as consumer electronics and electrical vehicles. There are a number of important parameters that determine the suitability of electrode materials for battery applications, such as the average voltage and the maximum specific capacity which contribute to the overall energy density. Another important performance criterion for battery electrode materials is their volume change upon charging and discharging, which contributes to determine the cyclability, Coulombic efficiency, and safety of a battery. In this work, we present deep neural network regression machine learning models (ML), trained on data obtained from the Materials Project database, for predicting average voltages and volume change upon charging and discharging of electrode materials for metal-ion batteries. Our models exhibit good performance as measured by the average mean absolute error obtained from a 10-fold cross-validation, as well as on independent test sets. We further assess the robustness of our ML models by investigating their screening potential beyond the training database. We produce Na-ion electrodes by systematically replacing Li-ions in the original database by Na-ions and, then, selecting a set of 22 electrodes that exhibit a good performance in energy density, as well as small volume variations upon charging and discharging, as predicted by the machine learning model. The ML predictions for these materials are then compared to quantum-mechanics based calculations. Our results reaffirm the significant role of machine learning techniques in the exploration of materials for battery applications.

Elevating Energy Density for Sodium-Ion Batteries through Multielectron Reactions.

It remains a great challenge to explore desirable cathodes for sodium-ion batteries to satisfy the ever-increasing demand for large-scale energy storage systems. In this Letter, we report a NASICON-structured Na4MnCr(PO4)3 cathode with high specific capacity and operation potential. The reversible access of the Mn2+/Mn3+ (3.75/3.4 V), Mn3+/Mn4+ (4.25/4.1 V), and Cr3+/Cr4+ (4.4/4.3 V vs Na/Na+) redox couples in a Na4MnCr(PO4)3 cathode endows a distinct three-electron redox reaction during the insertion/extraction process. The highly stable NASICON structure with a small volume variation upon cycling ensures long-time cycling stability (73.3% capacity retention after 500 cycles within the potential region of 2.5-4.6 V). The impedance analysis and interface characterization indicate that the evolution of a cathode electrolyte interphase at high potential is correlated with the capacity fading, while the robustness of the NASICON framework is redemonstrated.

Understanding the electrochemical properties and phase transformations of layered VOPO4⋅H2O as a potassium-ion battery cathode

Layered oxovanadium phosphate hydrate (VOPO4·xH2O) is considered to be a promising cathode material for potassium-ion batteries. However, its correlation between electrochemical properties and structural changes during electrochemical processes still need further exploration. Herein, monohydrate VOPO4·H2O is used as an alkali ion (Li+, Na+, K+) host material that gives superior electrochemical performances in potassium-ion batteries. It has a high discharge capacity of 90 mA h g−1 with a high average potential of 3.5 V and a lifespan of over 650 cycles with 61% retention at 1C rate. Three phase transitions during the potassiation/depotassiation process are observed: KxVOPO4 (0 < x < 0.12, d = 7.06 Å) → αI-KxVOPO4 (0.12 < x < 0.48, d = 6.73 Å) → αII-KxVOPO4 (0.30 < x < 0.55, d = 6.55 Å). The small structural change (≤6% on the c-axis) and the full reversibility of the structural transformation ensure the stable cycling; the large interlayer distance allows a fast K-ion diffusion (10−9–10−11 cm2 s−1). This study provides a comprehensive understanding on electrochemical performances and structural evolutions of VOPO4·H2O. Meanwhile, the small volume variation, high operating potential, and excellent cycling stability of VOPO4·H2O can attract more attention to develop other layered materials beyond transition metal oxides.

The First-Principles Prediction of Two Dimensional Monolayer Puckered WCAZ2 as the Anode Material of Li-ion Batteries

Searching for new high performance anode materials for Li-ion batteries(LIB) have become a critical issue in the current development of power source storage. In this paper, we theoretically predict a new kind of two dimensional transition metal carbide structure WC2, which is similar to MXene materials. The monolayer puckered WC2 is rather thermodynamically stable which can be demonstrated by the none imaginary frequency in the phonon spectrum and the entire structure after 5 ps ab initio molecular dynamic simulation at 300 K. The monolayer WC2 has the metallic character, hence ensures the fast electron transport during the lithiation/delithiation process. The moderate average adsorption energy of Li atoms (2.16 eV) and low diffusion energy barrier of Li (0.34 eV) on the surface prove that the monolayer WC2 has high charge/discharge rate and is suitable for the LIB anode. The maximum gravimetric capacity of numerous Li atoms adsorbed monolayer WC2 reaches 516 mA h/g, which is comparable to that of other MXene anodes. The small volume variation ratio(< 5 %) of the WC2 anode ensures the excellent cycling performance for LIBs. The electron transfer and orbital hybridization between Li and the monolayer WC2 indicate its excellent properties. Thus, the monolayer WC2 should be a promising anode material for the LIBs.

Realizing Complete Solid-Solution Reaction in High Sodium Content P2-Type Cathode for High-Performance Sodium-Ion Batteries.

P2-type layered oxides suffer from an ordered Na+ /vacancy arrangement and P2→O2/OP4 phase transitions, leading them to exhibit multiple voltage plateaus upon Na+ extraction/insertion. The deficient sodium in the P2-type cathode easily induces the bad structural stability at deep desodiation states and limited reversible capacity during Na+ de/insertion. These drawbacks cause poor rate capability and fast capacity decay in most P2-type layered oxides. To address these challenges, a novel high sodium content (0.85) and plateau-free P2-type cathode-Na0.85 Li0.12 Ni0.22 Mn0.66 O2 (P2-NLNMO) was developed. The complete solid-solution reaction over a wide voltage range ensures both fast Na+ mobility (10-11 to 10-10 cm2 s-1 ) and small volume variation (1.7 %). The high sodium content P2-NLNMO exhibits a higher reversible capacity of 123.4 mA h g-1 , superior rate capability of 79.3 mA h g-1 at 20 C, and 85.4 % capacity retention after 500 cycles at 5 C. The sufficient Na and complete solid-solution reaction are critical to realizing high-performance P2-type cathodes for sodium-ion batteries.

Realizing Complete Solid‐Solution Reaction in High Sodium Content P2‐Type Cathode for High‐Performance Sodium‐Ion Batteries

AbstractP2‐type layered oxides suffer from an ordered Na+/vacancy arrangement and P2→O2/OP4 phase transitions, leading them to exhibit multiple voltage plateaus upon Na+ extraction/insertion. The deficient sodium in the P2‐type cathode easily induces the bad structural stability at deep desodiation states and limited reversible capacity during Na+ de/insertion. These drawbacks cause poor rate capability and fast capacity decay in most P2‐type layered oxides. To address these challenges, a novel high sodium content (0.85) and plateau‐free P2‐type cathode‐Na0.85Li0.12Ni0.22Mn0.66O2 (P2‐NLNMO) was developed. The complete solid‐solution reaction over a wide voltage range ensures both fast Na+ mobility (10−11 to 10−10 cm2 s−1) and small volume variation (1.7 %). The high sodium content P2‐NLNMO exhibits a higher reversible capacity of 123.4 mA h g−1, superior rate capability of 79.3 mA h g−1 at 20 C, and 85.4 % capacity retention after 500 cycles at 5 C. The sufficient Na and complete solid‐solution reaction are critical to realizing high‐performance P2‐type cathodes for sodium‐ion batteries.

Understanding rhombohedral iron hexacyanoferrate with three different sodium positions for high power and long stability sodium-ion battery

Sodium iron hexacyanoferrate (NaFeHCF) has been considered as a potential cathode for sodium-ion batteries owing to its low-cost and easily prepared procedure. However, it is still challenging to achieve long cyclic stability and superior rate capability, and the sodium storage mechanism of sodium-rich NaFeHCF is still elusive. Herein, a sodium-rich NaFeHCF with rhombohedral structure is presented with excellent electrochemical performances within 2.0–4.2 ​V. The specific capacity of ~115 ​mA ​h ​g−1 is obtained by utilizing two plateaus around 2.9 and 4.06 ​V, respectively. Remarkable rate performance from 10 to 4000 ​mA ​g−1 and 1000 cycles with high capacity retention is achieved as well. Synchrotron powder X-ray diffraction (PXRD) and structural refinement reveals that sodium-ions occupy three different sites (interstitial, face and edge) in rhombohedral unit cell, which contribute different capacities on different plateaus during Na+ extractions. Moreover, the rhombohedral structure is well-maintained after long-term Na+ extractions/insertions and reversible phase transitions with small volume variation are observed through in-situ synchrotron PXRD. The kinetic properties of Na+ in rhombohedral unit cell are identified by ab-initio molecular dynamics method and density functional theory calculations, which indicate that Na+ transport on three-dimensional diffusion paths, thus enabling the outstanding rate performance of NaFeHCF.

Evaluating the effects of micro-zones of granular sludge on one-stage partial nitritation-anammox nitrogen removal.

The one-stage partial nitritation-anammox (PN-A) process is considered an efficient process for low-cost nitrogen removal. In this study, the nitrogen removal performance of different-sized granules in a one-stage PN-A reactor was studied. The total autotrophic nitrogen removal rate (TANRR) of the granular sludge increased as the granule size increased, and the TANRR of granular sludge with a radius larger than 500μm reached 0.14 kgNkgVSS-1d-1. High-throughput sequencing revealed that the abundance of ammonium-oxidizing bacteria and anaerobic ammonium-oxidizing (anammox) bacteria in granular sludge of different sizes differed, indicating that the bacterial community structure was affected by the granule size. The TANRR of different-sized granules was affected by the volumes of aerobic micro-zone and anaerobic micro-zone inside the granule. Appropriate micro-zone volumes inside the granules could be regulated by the dissolved oxygen (DO) concentration of the reactor, which are favourable for achieving a balance between partial nitritation and anammox and then satisfactory nitrogen removal. Small-volume variations in the range of micro-zones have a significant influence on the balance between partial nitritation and anammox. The proper DO concentration required for different-sized granules to achieve better nitrogen removal differed. This study provides a novel perspective for understanding the effect of micro-zones of granular sludge on one-stage PN-A nitrogen removal.

Serum tRNA-derived fragments (tRFs) as potential candidates for diagnosis of nontriple negative breast cancer.

Breast cancer has become the most common cancer in women, and nontriple negative breast cancer (non-TNBC) accounts for 80-90% of all invasive breast cancers. Early detection, diagnosis, and treatment are considered key to a successful cure. Conventionally, breast imaging and needle core biopsy are used for detection and monitoring. However, small variations in volume might be ignored in imaging, and traditional biopsies are spatially and temporally limited, leading to a significant delay in cancer detection and thus prompting renewed focus on early and accurate diagnosis. In this article, we investigated whether there is an accurate molecule in peripheral blood that can help diagnose breast cancer. Similar to microRNAs, tRNA-derived fragments (tRFs) have been reported to be involved in many pathological processes in breast cancer, but whether they can serve as candidate biomarkers for breast cancer remains unclear. Using high-throughput sequencing technology, we identified 4,021 differentially expressed tRFs in normal and breast cancer cell lines, and eight tRFs were selected to establish a signature as a predictive biomarker of non-TNBC. Furthermore, quantitative reverse-transcriptase polymerase chain reaction was performed to verify the expression of the signature and analyze the correlation between dysregulated tRFs and breast cancer. The results indicated that tDR-7816, tDR-5334, and tDR-4733 might be promising biomarkers. Through further bioinformatics analysis, we predicted that tDR-7816 influences the xenobiotic metabolic processes that support the oncogenesis of breast cancer. In summary, our results provide a rationale for using circulating tDR-7816 expression as a novel potential biomarker for the diagnosis of patients with early non-TNBC.