A Hybrid Redox-Mediated Zinc-Air Fuel Cell for Scalable and Sustained Power Generation.

Zinc-air batteries (ZABs) have attracted considerable attention for their high energy density, safety, low noise, and eco-friendliness. However, the capacity of mechanically rechargeable ZABs was limited by the cumbersome procedure for replacing the zinc anode, while electrically rechargeable ZABs suffer from issues including low depth of discharge, zinc dendrite and dead zinc formation, and sluggish oxygen evolution reaction, etc. To address these issues, we report a hybrid redox-mediated zinc-air fuel cell (HRM-ZAFC) utilizing 7,8-dihydroxyphenazine-2-sulfonic acid (DHPS) as the anolyte redox mediator, which shifts the zinc oxidation reaction from the electrode surface to a separate fuel tank. This approach decouples fuel feeding and electricity generation, providing greater operation flexibility and scalability for large-scale power generation applications. The DHPS-mediated ZAFC exhibited a superior peak power density of 0.51 W/cm2 and a continuous discharge capacity of 48.82 Ah with ZnO as the discharge product in the tank, highlighting its potential for power generation.

Serum Metabolic Characterization of Vitamin E Deficiency in Holstein Cows during the Transition Period Based on Proton Nuclear Magnetic Resonance Spectroscopy.

Vitamin E, a potent antioxidant, is a necessary and complex micronutrient for cows. During the transition period, vitamin E deficiency (VED) is among the highest prevalent micronutrient deficits in dairy cows. It may eventually result in oxidative stress and immunological malfunction, and it increases the risk of peripartum disorders. At present, detailed data on blood metabolites in VED cows are limited. Consequently, the purpose of this research was to examine the alterations in the serum metabolic profile of VED cows throughout the early postpartum period. Using comprehensive 1H nuclear magnetic resonance (1H NMR), the alterations in serum metabolic activities of VED cows were analyzed. In total, 28 multiparous Holstein cows were assigned according to serum α-tocopherol (α-Toc) concentrations into normal (α-Toc ≥ 4 µg/mL, n = 14) and VED (α-Toc < 3 µg/mL, n = 14) groups at 21 days postpartum, and their blood samples were collected for biochemical and 1H NMR analyses. A t-test on independent samples as well as multivariate statistics were used to assess the findings. In comparison with normal cows, VED cows showed significantly worse body condition scores, milk yield, and dry matter intake (p < 0.05). Significantly higher levels of serum non-esterified fatty acids, aspartate aminotransferase, low-density lipoprotein, and malonaldehyde were found in VED-affected cows, as well as lesser concentrations of serum albumin, high-density lipoprotein, and total antioxidant capacity in comparison with normal cows (p < 0.01), while other vitamins and minerals concentrations showed no distinction between the groups (p > 0.05). Furthermore, 24 upregulated serum metabolites were identified under VED conditions. The metabolomics pathway analysis of these metabolites demonstrated that a global metabolic response to VED in cows was represented by changes in 11 metabolic pathways, comprising energy, carbohydrate, and amino acid metabolism. From these results, we conclude that VED cows were more likely to experience a negative energy balance characterized by alterations of common systemic metabolic processes and develop oxidative stress, inflammation, and ultimately liver injury. This study provides the first evidence of metabolic changes in cows with VED.

Copper nanoclusters electrochemiluminescence with tunable near-infrared emission wavelength for ultrasensitive detection of matrix metalloproteinase-2.

Herein, the methionine (Met)/N-acetyl-L-cysteine (NAC) templated copper nanoclusters (Met/NAC-Cu NCs) with tunable near-infrared region (NIR) electrochemiluminescence (ECL) emission wavelength was firstly synthesized as emitter for the ultrasensitive detection of matrix metalloproteinase-2 (MMP-2). Significantly, the NAC played the role of template and reductant of cupric to acquire Cu NCs, and the surface defect regulator Met was used to connect NAC through -S-S- bond, which could heighten the surface defect of Cu NCs to continuously regulate the maximum ECL emission by successively controlling the molar ratio of Met and NAC, leading to the ECL emission wavelength of Cu NCs ranged from 680 nm to 750 nm. In addition, a rapid target triggered catalyst hairpin assembly (CHA) recycling amplification strategy was constructed through orderly and equidistantly arranging hairpin to increase its local concentration, resulting in greatly accelerated signal amplification efficiency and reaction rate. As a proof of concept, based on Met/NAC-Cu NCs as NIR ECL emitter and effective signal amplification tactic, a super-sensitive ECL biosensor was fabricated to detect target MMP-2 with the detection limit (LOD) as low as 1.65 fg/mL and successfully utilized for detecting of MMP-2 that from Hela and MCF-7 cancer cells. This research provided a wonderful avenue for regulating the optical performance of metal nanoclusters-based ECL emitters, and the developed neoteric NIR ECL emitter with the merits of less photochemical damage and deeper tissue penetration exhibited great potential in ultrasensitive biosensing and high-definition ECL imaging.

Extracellular vesicles released by glioma cells are decorated by Annexin A2 allowing for cellular uptake via heparan sulfate.

Extracellular vesicles (EVs) play a crucial role in regulating cell behavior by delivering their cargo to target cells. However, the mechanisms underlying EV-cell interactions are not well understood. Previous studies have shown that heparan sulfate (HS) on target cell surfaces can act as receptors for exosomes uptake, but the ligand for HS on EVs has not been identified. In this study, we isolated EVs from glioma cell lines and glioma patients and identified Annexin A2 (AnxA2) on EVs as a key HS-binding ligand and mediator of EV-cell interactions. Our findings suggest that HS plays a dual role in EV-cell interactions, where HS on EVs captures AnxA2, and on target cells, it acts as a receptor for AnxA2. Removal of HS from the EV surface inhibits EV-target cell interaction by releasing AnxA2. Furthermore, we found that AnxA2-mediated binding of EVs to vascular endothelial cells promotes angiogenesis, and that antibody against AnxA2 inhibited the ability of glioma-derived EVs to stimulate angiogenesis by reducing the uptake of EVs. Our study also suggests that the AnxA2-HS interaction may accelerate the glioma-derived EVs-mediated angiogenesis and that combining AnxA2 on glioma cells with HS on endothelial cells may effectively improve the prognosis evaluation of glioma patients.

Simultaneous Regulation of Solvation Shell and Oriented Deposition toward a Highly Reversible Fe Anode for All-Iron Flow Batteries.

Developing low-cost all-iron hybrid redox flow batteries (RFBs) presents a practical alternative to the high-cost all-vanadium RFBs and is deemed vital for grid-scale energy storage applications. However, the intrinsically poor Fe anode reversibility associated with the deposition and dissolution of metallic iron greatly limits the cycling performance and long-term stability of all-iron hybrid RFBs. Herein, a highly reversible and dendrite-free Fe anode is reported for all-iron RFBs through regulation of polar solvent dimethyl sulfoxide (DMSO) on FeCl2 anolyte, which simultaneously reshapes Fe2+ solvation structure and induces controllable oriented Fe deposition. Combining both experimental and theoretical analyses, the polar DMSO additives prove effective in replacing H2 O molecule from the primary solvation shell of Fe2+ cation via the Fe2+ -O (DMSO) bond and meanwhile induces a fine-grained Fe nucleation on the preferred Fe (110) plane, which are responsible for the minimized hydrogen evolution and dendrite-free Fe deposition that significantly enhance Fe anode reversibility. The all-iron RFB based on the proposed FeCl2 -DMSO anolyte demonstrates an excellent combination of peak power density of 134 mW cm-2 , high energy efficiency of 75% at 30 mA cm-2 , and high capacity retention of 98.6% over 200 cycles, which presents the best performance of all-iron RFBs among previously reported research.

High-Power Near-Neutral Aqueous All Organic Redox Flow Battery Enabled with a Pair of Anionic Redox Species.

Aqueous organic redox flow batteries (AORFBs) are regarded as a promising alternative for low-cost and durable grid-scale energy storage. However, the narrow potential gap, chemical lability and membrane fouling in most AORFBs constitute formidable roadblocks for practical applications. Herein, a pair of anionic organic molecules, namely (PPBPy)Br2 and PSS-TEMPO, are proposed. The (PPBPy)Br2 in anolyte reveals remarkable electrochemical stability without degradation after 1000 cycles, while PSS-TEMPO in catholyte presents a capacity decay rate as low as 0.012 %/cycle. At near-neutral conditions, the (PPBPy)Br2 /PSS-TEMPO flow cell exhibits a high voltage of 1.61 V, extremely low permeability across cation-exchange membrane and thus excellent cycling stability. Notably, a highest peak power density of 509 mW cm-2 has been achieved among reported all-organic aqueous RFBs. The molecular engineering strategies demonstrated here could provide a credible example of high-performance AORFBs.

Left displacement of the third gastric compartment in an alpaca: the first case report in China.

BACKGROUND: Left displacement of the third gastric compartment (LDC3) in alpacas is an extremely rare condition and has not been reported thus far. Therefore, we describe the clinical diagnosis and treatment of LDC3 in an alpaca. CASE PRESENTATION: A 2-year-old brown female alpaca (Vicugna pacos) was presented to evaluate a 3-day history of abdominal distension causing loss of both appetite and thirst, along with oliguria and low to no defecation. Clinical examination, X-ray examination, surgical exploration, and determination of gastric pH (pH ~ 2.35) confirmed that LDC3 resulted in abdominal distension. The gastric wall of the displaced third gastric compartment was incised for the expulsion of pneumatosis, and a medical-grade silicone tube was inserted into the incision to remove the effusion by siphoning. Surgical treatment proved to effectively alleviate the abdominal distension caused by LDC3 without apparent side effects. CONCLUSIONS: To our knowledge, this case is the first known report of LDC3 in an alpaca in China. A similar condition, left displaced abomasum, has previously been described in cattle and sheep.

Metabolite Comparison between Serum and Follicular Fluid of Dairy Cows with Inactive Ovaries Postpartum.

Inactive ovaries (IO) accounts for 50% of ovarian disease in postpartum dairy cows, which seriously affects their reproductive efficiency. To investigate the metabolic changes in the serum and follicular fluid of dairy cows with IO during lactation, six estrus (E) cows and six IO cows at 50 to 55 days in milk were selected based on B ultrasonic detection and clinical manifestations. The differential metabolites in serum and follicular fluid between the E cows and IO cows were identified by ultra-high-pressure liquid chromatography-quadrupole time-of-flight mass spectrometry, combined with multidimensional statistical methods. The results showed that dairy cows with IO were in a subclinical ketosis status where beta-hydroxybutyrate (BHB) exceeded 1.20 mmol/L, 14 differential metabolites in the serum of IO cows included 10 increased metabolites and 4 decreased metabolites, and 14 differential metabolites in the follicular fluid of IO cows included 8 increased metabolites and 6 decreased metabolites. These differential metabolites mainly involved nine metabolic pathways. The common enrichment pathway of different metabolites in serum and follicular fluid were glycerophospholipid metabolism and pentose and glucuronate interconversions. In conclusion, there were significant differences in the differential metabolites and enrichment pathways between serum and follicular fluid of IO cows, implying that there were complex changes in blood metabolism and local follicular metabolism of IO cows, whose interactions need further investigation.

Early Warning for Ovarian Diseases Based on Plasma Non-esterified Fatty Acid and Calcium Concentrations in Dairy Cows.

Inactive ovaries (IO) and ovarian (follicular or luteal) cysts (FC or LC) are two common ovarian diseases leading to infertility in dairy cattle. Both disorders are associated with altered metabolites and hormones. There are currently no known effective biomarkers that can be used for early diagnosis of ovarian diseases. The purpose of this study was to identify the plasma biomarkers of ovarian diseases in Holstein dairy cows that facilitate an early diagnosis of the diseases and control its progression. The experiment was performed from 3 weeks postpartum and last for 7 weeks. Seventy-six multiparous Holstein cows (mean age, 4.36 years; weight, 635.63 kg) were divided into healthy control group (HC, n = 22), FC group (n = 18), LC group (n = 18) and IO group (n = 18) by rectal palpation or ultrasonography during the last 2 weeks before trial end. Blood was collected via tail vein for measurement of plasma energy metabolites, liver function indicators, minerals, and hormones at 3 and 8 weeks postpartum. Data were analyzed by Mann-Whitney U, Kruskal-Wallis, Spearman correlation, binary logistic regression analysis and receiver operating characteristic analysis, where applicable. At 8 weeks postpartum, FC cows had a more severe body condition score loss and these had greater levels of non-esterified fatty acids (NEFA) and estradiol, and lesser levels of alanine aminotransferase (ALT), progesterone and insulin-like growth factor 1 (IGF-1) levels than HC cows (P < 0.05). LC cows had a lower milk yield, higher NEFA and progesterone levels, and lower calcium, phosphorus and magnesium levels than HC cows (P < 0.05). IO cows had a lower body condition score, higher NEFA levels, and lower ALT, calcium, phosphorus, magnesium, estradiol, progesterone and IGF-1 levels than HC cows (P < 0.05). At 3 weeks postpartum, cows with ovarian diseases had greater (P < 0.05) concentrations of NEFA, and lesser concentrations of ALT, calcium, phosphorus and IGF-1 than HC cows. Early warning values for ovarian diseases were plasma NEFA concentrations >0.50 mmol/L, or calcium concentrations <2.02 mmol/L. Therefore, plasma NEFA and calcium could be used as early-warning indicators for ovarian diseases in dairy cows.

Effect of Negative Energy Balance on Plasma Metabolites, Minerals, Hormones, Cytokines and Ovarian Follicular Growth Rate in Holstein Dairy Cows.

INTRODUCTION: The aim of this study was to evaluate the effect of negative energy balance (NEB) on the final growth of the dominant ovarian follicle in Holstein cows. MATERIAL AND METHODS: Cows at 14 to 21 d postpartum from an intensive dairy farm were randomly selected and allocated into a positive energy balance group (PEB, with ß-hydroxybutyric acid (BHBA) level < 1.2 mmol/L, n = 15) and an NEB group (BHBA > 1.2 mmol/L, n = 15). Plasma samples were collected at 21, 50 and 55 d postpartum to assess the concentrations of energy metabolites, minerals, hormones and cytokines. Ovaries were examined by transrectal ultrasound on days 50 and 55 (120 hours later) to evaluate the diameter of the largest follicle. RESULTS: Compared with PEB cows, there were a more severe body condition loss and a lower milk yield in NEB cows (P < 0.05) and these had greater concentrations of plasma BHBA, non-esterified fatty acids, triglycerides, urea nitrogen, growth hormone, interleukin 6, and fibroblast growth factor 21 and lesser concentrations of plasma glucose, total cholesterol, insulin, insulin-like growth factor 1, insulin-like growth factor binding protein 3, leptin, brain-derived neurotrophic factor and angiopoietin-like protein 8 on d 21 (P < 0.05), while plasma minerals were not affected by energy status (P > 0.05). These changes persisted until the end of the study period (50-55 days postpartum) resulting in a lower follicular growth rate for cows in the NEB than the PEB group. CONCLUSION: These observations indicate that follicular growth rate is associated with measurable changes in energy metabolite, hormone and cytokine concentrations caused by early postpartum NEB.

GC/MS and LC/MS Based Serum Metabolomic Analysis of Dairy Cows With Ovarian Inactivity.

Metabolic disorders may lead to the inactive ovaries of dairy cows during early lactation. However, the detailed metabolic profile of dairy cows with inactive ovaries around 55 days postpartum has not been clearly elucidated. The objective of this study was to investigate the metabolic difference in cows with inactive ovaries and estrus from the perspective of serum metabolites. According to clinical manifestations, B-ultrasound scan, rectal examination, 15 cows were assigned to the estrus group (E; follicular diameter 15-20 mm) and 15 to the inactive ovary group (IO; follicular diameter <8 mm and increased <2 mm within 5 days over two examinations). The blood was collected from the tail vein of the cow to separate serum 55-60 days postpartum, and then milked and fasted in the morning. Serum samples were analyzed using gas chromatography time-of-flight mass spectrometry technology (GC-TOF-MS) and ultra-high-pressure liquid chromatography-quadrupole-time-of-flight mass spectrometry (UHPLC-QTOF-MS). Differences in serum metabolites were identified using multivariate statistical analysis and univariate analysis. Thirty differentially abundant metabolites were identified between the two groups. In cows with inactive ovaries compared with cows in estrus, 20 serum metabolites were significantly higher (beta-cryptoxanthin (p = 0.0012), 9-cis-retinal (p = 0.0030), oxamic acid (p = 0.0321), etc.) while 10 metabolites were significantly lower (monostearin (p = 0.0001), 3-hydroxypropionic acid (p = 0.0005), D-talose (p = 0.0018), etc.). Pathway analysis indicated that the serum differential metabolites of multiparous cows in estrus obtained by the two metabolomics techniques were mainly involved in ß-alanine metabolism and steroid biosynthesis metabolism, while other involved metabolic pathways were related to metabolism of glyoxylate; dicarboxylate metabolism; fructose, mannose, glutathione, glycerolipid, glycine, serine, threonine, propanoate, retinol, and pyrimidine metabolism. This indicates that the abnormalities in glucose metabolism, lipid metabolism, amino acid metabolism, and glutathione metabolism of postpartum dairy cows obstructed follicular development.

Overexpression of Annexin A2 promotes proliferation by forming a Glypican 1/c-Myc positive feedback loop: prognostic significance in human glioma.

In order to set up a reliable prediction system for the tumor grade and prognosis in glioma patients, we clarify the complicated crosstalk of Annexin A2 (ANXA2) with Glypican 1 (GPC1) and demonstrate whether combined indexes of ANXA2 and GPC1 could improve the prognostic evaluation for glioma patients. We found that ANXA2-induced glioma cell proliferation in a c-Myc-dependent manner. ANXA2 increased the expression of GPC1 via c-Myc and the upregulated GPC1 further promoted the c-Myc level, forming a positive feedback loop, which eventually led to enhanced proliferation of glioma cells. Both mRNA and protein levels of ANXA2 were upregulated in glioma tissues and coincided with the overexpression of GPC1. Besides, we utilized tissue microarrays (TMAs) and immunohistochemistry to demonstrate that glioma patients with both high expression of ANXA2 and GPC1 tended to have higher rate of tumor recurrence and shorter overall survival (OS). In conclusion, the overexpression of ANXA2 promotes proliferation of glioma cells by forming a GPC1/c-Myc positive feedback loop, and ANXA2 together with its downstream target GPC1 could be a potential "combination biomarker" for predicting prognosis of glioma patients.

miR-17-5p and miR-19b-3p prevent osteoarthritis progression by targeting EZH2.

Osteoarthritis (OA) is a joint disease caused by a variety of factors, including aging, obesity and trauma. MicroRNAs (miRNAs) have been reported to be crucial regulators during OA progression. The present study aimed to investigate the role of miR-17-5p and miR-19b-3p during OA development. Interleukin (IL)-1ß-treated chondrocytes were used to mimic OA in vitro. The expression levels of miR-17-5p and enhancer of zeste homolog 2 (EZH2) were measured in cartilage tissues and chondrocytes using reverse transcription-quantitative PCR or western blotting. Apoptosis was assessed by flow cytometry. The protein expression levels of extracellular matrix (ECM)-associated genes were detected by western blotting. The binding sites between miR-17-5p or miR-19b-3p and EZH2 were predicted using the MicroT-CDS online database and verified using dual-luciferase reporter and RIP assays. miR-17-5p expression was downregulated, whereas EZH2 expression was upregulated in OA cartilage tissues and IL-1ß-induced chondrocytes compared with that in the control tissues and cells. miR-17-5p mimics inhibited IL-1ß-induced apoptosis and ECM degradation in chondrocytes. EZH2 was the target of miR-17-5p and miR-19b-3p in chondrocytes, and enhanced apoptosis and ECM degradation in IL-1ß-stimulated chondrocytes. Rescue experiments revealed that miR-17-5p or miR-19b-3p mimic-induced inhibition of OA progression was reversed by EZH2 overexpression. In conclusion, miR-17-5p and miR-19b-3p inhibited OA progression by targeting EZH2, which may serve as a potential therapeutic target for OA.

Zingerone Promotes Osteoblast Differentiation Via MiR-200c-3p/smad7 Regulatory Axis in Human Bone Mesenchymal Stem Cells.

BACKGROUND Osteoblast differentiation is a critical process to maintain the stability of the bone homeostasis. Zingerone, 4-(4-hydroxy-3-methoxyphenyl)-2-butanone (ZG), isolated from ginger, performs a wide range of biological functions in human diseases. The objective of this paper was to clarify the role of ZG in human bone mesenchymal stem cells (hBMSCs) and associated mechanisms of ZG promoting osteoblast differentiation. MATERIAL AND METHODS The cytotoxicity of ZG was detected by MTT assay. The expression levels of miR-200c-3p, smad7, and osteoblast differentiation markers (alkaline phosphatase [ALP], osteocalcin [OC], osterix [OSX] and runt-related transcription factor 2 [RUNX2]) were assessed by quantitative real-time polymerase chain reaction (qRT-PCR). The protein levels of smad7, ALP, OC, OSX, and RUNX2 were quantified by western blot analysis. The target mRNAs were predicted by bioinformatics tools TargetScan. The interaction between miR-200c-3p and smad7 was verified by luciferase reporter assay and RIP assay. RESULTS ZG was nontoxic to hBMSCs, and it accelerated osteoblast differentiation by inducing the expression of ALP, OC, OSX, and RUNX2. MiR-200c-3p was upregulated, but smad7 was downregulated in hBMSCs treated with ZG at different concentrations at different periods. Besides, miR-200c-3p positively regulated the expression of ALP, OC, OSX, and RUNX2 in ZG-induced hBMSCs. Moreover, miR-200c-3p targeted smad7 and strengthened the expression of ALP, OC, OSX, and RUNX2 in ZG-induced hBMSCs by downregulating smad7. CONCLUSIONS ZG contributed to osteoblast differentiation via miR-200c-3p/smad7 regulatory axis by promoting the expression of ALP, OC, OSX, and RUNX2 in hBMSCs.

Plasma Metabolic Characterisation of Dairy Cows with Inactive Ovaries and Oestrus During the Peak of Lactation.

INTRODUCTION: Differential metabolites (DMs) between cows with inactive ovaries (IO) and oestrous (E) cows were screened and metabolic pathways of DMs associated with IO were determined. MATERIAL AND METHODS: Cows at 50 to 60 days (d) postpartum from an intensive dairy farm were randomly selected and allocated into an E group (n = 16) or an IO group (n = 16) according to a pedometer and rectal examinations. Their plasma samples were analysed by liquid chromatography-mass spectrometry (LC-MS) to compare plasma metabolic changes between the E and IO groups. Multivariate pattern recognition was used to screen the DMs in the plasma of IO cows. RESULTS: Compared with normal E cows, there were abnormalities in 20 metabolites in IO cows, including a significantly decreased content (VIP > 1, P < 0.05) of cholic acid, p-chlorophenylalanine, and arachidonic acid, and a significantly increased content (VIP > 1, P < 0.05) of tyramine, betaine, L-phenylalanine, L-glutamate, D-proline, L-alanine, and L-pyrophosphate. Five DMs (cholic acid, D-proline, L-glutamate, L-alanine, and L-pyroglutamic acid) with higher variable importance in projection (VIP) values between groups were validated by ELISA with blind samples of re-selected cows (IO, 50 to 60 d postpartum) and the validated results were consistent with the LC-MS results. CONCLUSION: The 20 DMs in IO cows during the peak of lactation indicated that the pathogenesis of IO was involved in complex metabolic networks and signal transduction pathways. This study provides a basis for further exploration of the pathogenesis and prevention of IO in cows in the future.

Redox dual-responsive paclitaxel-doxorubicin heterodimeric prodrug self-delivery nanoaggregates for more effective breast cancer synergistic combination chemotherapy.

A single nanodrug delivery system for combined delivery of paclitaxel and doxorubicin that integrates high co-loading efficiency, synchronous co-delivery of combined drugs, controllable drug release, and maintains the drug combination at fixed synergistic ratios has been proven to be challenging. Here, we report a redox dual-responsive prodrug nanosystem consisting of a paclitaxel-doxorubicin heterodimeric prodrug with a thioether bond linkage to effectively co-deliver two therapeutic drugs. The heterodimeric prodrug could self-assemble into uniform nanoaggregates containing DSPE-PEG2K with a precise drug co-loading ratio in water, and possessed a high co-loading content. We demonstrated that this nanosystem provided strong synergistic effects in MCF-7 and 4 T1 cells. In vivo, this nanosystem results in a long blood circulation, high accumulation in the tumor, and significant inhibition of tumor growth in BALB/c mice bearing 4 T1 tumors. Such a simple, safe, and efficient heterodimeric prodrug nanosystem exhibits great potential for clinical translation in future combination chemotherapy treatments.

First-principles study of enhanced magnetic anisotropies in transition-metal atoms doped WS2 monolayer.

Considerable progress in contemporary spintronics has been made in recent years for developing nanoscale data memory and quantum information processing. It is, however, still a great challenge to achieve the ultimate limit of storage bit. 2D materials, fortunately, provide an alternative solution for designing materials with the expected miniaturizing scale, chemical stability as well as giant magnetic anisotropy energy. By performing first-principles calculations, we have examined two possible doping sites on a WS2 monolayer using three kinds of transition metal (TM) atoms (Mn, Fe and Co). It is found that the TM atoms prefer to stay on the W atom site. Additionally, differently from the case of Mn, doping Co and Fe atoms on the W vacancy can achieve perpendicular magnetic anisotropy with a much larger magnitude, which provides a bright prospect for generating atomic-scale magnets of storage devices.