基于机器学习的Al-Zn-Mg-Cu合金快速设计

提出一种基于机器学习的合金快速设计系统(ARDS),以定制所需性能的合金制备策略或预测制备策略所对应的合金性能。为此,分别对3种回归算法:线性回归(LR)、支持向量回归(SVR)和人工神经网络(BPNN)进行建模和比较以训练多性能预测模型。其中,应用SVR构建的机器学习模型被证明是最佳的。然后,基于生成对抗网络(GAN)模型原理,构建Al-Zn-Mg-Cu系铝合金快速设计系统(ARDS)。对ARDS的预测可靠性进行验证。结果表明,为了能够获得准确的制备策略,系统中极限抗拉强度(UTS)、屈服强度(YS)和伸长率(EL)的输入上限分别约为790 MPa、730 MPa和28%。此外,基于ARDS预测结果,制备了一种性能优异的新型铝合金材料,其UTS为764 MPa、YS为732 MPa、EL为10.1%,进一步验证了ARDS的可靠性。

Al-20%Cu多晶粒竞争生长的原位观测及汇聚型枝晶淘汰模型构建

采用同步辐射成像技术研究Al-20%Cu(质量分数)亚共晶合金的晶粒竞争生长动力学,并建立与实验结果相一致的数学模型。结果表明,对于发散型竞争生长,遵循“正常淘汰”规则。对于汇聚型竞争生长,成分过冷的作用加速非择优取向晶粒中一次枝晶臂的生长速度,导致非择优取向枝晶出现“异常淘汰”现象,淘汰择优取向枝晶。探讨汇聚型竞争生长的“正常淘汰”与“异常淘汰”之间的临界条件,建立枝晶生长速率、枝晶臂间距和枝晶倾斜角之间的数学关系,又称“二次枝晶臂阻挡模型”,可以快速预测晶界位相和淘汰类型。

Rational design of vitamin C/defective carbon van der Waals heterostructure for enhanced activity,durability and storage stability toward oxygen reduction reaction

Metal-free defective carbon materials with abundant active sites have been widely studied as low-cost and efficient oxygen reduction reaction(ORR)electrocatalysts in metal-air batteries.However,the active sites in defective carbon are easily subjected to serious oxidation or hydroxylation during ORR or storage,leading to rapid degradation of activity.Herein,we design a van der Waals heterostructure comprised of vitamin C(VC)and defective carbon(DC)to not only boost the activity but also enhance the durability and storage stability of the DC-VC electrocatalyst.The formation of VC van der Waals between DC and VC is demonstrated to be an effective strategy to protect the defect active sites from oxidation and hydroxylation degradation,thus significantly enhancing the electrochemical durability and storage anti-aging performance.Moreover,the DC-VC van der Waals can reduce the reaction energy barrier to facilitate the ORR.These findings are also confirmed by operando Fourier transform infrared spectroscopy and density functional theory calculations.It is necessary to mention that the preparation of this DC-VC electrocatalyst can be scaled up,and the ORR performance of the largely produced electrocatalyst is demonstrated to be very consistent.Furthermore,the DC-VC-based aluminum-air batteries display very competitive power density with good performance maintenance.

MAPK9 as a therapeutic target:unveiling ferroptosis in localized prostate cancer progression

Background:Ferroptosis,a lipid peroxidation-mediated programmed cell death,is closely linked to tumor development,including prostate cancer(PCa).Despite established connections between ferroptosis and PCa,a comprehensive investigation is essential for understanding its impact on patient prognosis.Methods:A risk model incorporating four ferroptosis-related genes was developed and validated.Elevated risk scores correlated with an increased likelihood of biochemical recurrence(BCR),diminished immune infiltration,and adverse clinicopathological characteristics.To corroborate these results,we performed validation analyses utilizing datasets from both the Cancer Genome Atlas Cohort(TCGA)and the Gene Expression Synthesis Cohort(GEO).Moreover,we conducted further investigations into the pivotal gene identified in our model to explore its impact on tumor characteristics through cell proliferation and invasion assays,as well as animal studies conducted in vivo.Additionally,we conducted further experiments involving ferroptosis-related analysis to validate its association with ferroptosis.Results:The risk model demonstrated exceptional predictive capabilities for prognosis and therapeutic outcomes in PCa patients.Mitogen-activated protein kinase 9(MAPK9)emerged as a crucial gene within the model.In vivo and in vitro experiments explored MAPK9’s role in ferroptosis and its influence on tumor migration and proliferation.Conclusion:The findings provide a novel perspective for advancing ferroptosis exploration in PCa,bridging basic research and clinical applications.

采用同步辐射小角X射线散射技术研究Al−Mg−Si合金的析出强化行为

研究Al−Mg−Si合金在等温时效过程中的析出强化行为及其对力学性能的影响。利用原位同步辐射小角X射线散射(SAXS)技术和透射电子显微镜(TEM)对纳米析出相及其结构参数(尺寸、体积分数和数密度)进行表征。结果表明,棒状β''析出相优先沿其纵向尺寸生长,但径向尺寸在时效5 h后达到峰值。如预测与测量的屈服强度和硬度结果所示,纳米析出相的尺寸和体积分数的增大与析出强化定量相关。SAXS为Ashby−Orowan模型提供了更可靠的输入参数,这有助于提高模型的预测精度和泛化能力。研究表明,随着时效时间的延长,Al−Mg−Si合金预测力学性能的演变与β''析出相的平均半径和体积分数有关。

352-Gbit/s single line rate THz wired transmission based on PS-4096QAM employing hollow-core fiber

We successfully demonstrate 32-Gbaud Probabilistically Shaped 4096-ary Quadrature Amplitude Modulation(PS-4096QAM)TeraHertz(THz)signal wired transmission at 325 GHz over the 1-m Hollow-Core Fiber(HCF)in a photon-assisted THz-wave communication system.By employing advanced Digital Signal Processing(DSP)and the PS technique,the 352-Gbit/s line rate(288-Gbit/s net rate)delivery with a net Spectral Efficiency(SE)of 9 bit/s/Hz is realized in the experiment,satisfying the 0.86-Normalized Generalized Mutual Information(NGMI)Low-Density Parity-Check(LDPC)threshold.

Variant rs8400 enhances ALKBH5 expression through disrupting miR-186 binding and promotes neuroblastoma progression

Objective:AlkB homolog 5(ALKBH5)has been proven to be closely related to tumors.However,the role and molecular mechanism of ALKBH5 in neuroblastomas have rarely been reported.Methods:The potential functional single-nucleotide polymorphisms(SNPs)in ALKBH5 were identified by National Center for Biotechnology Information(NCBI)dbSNP screening and SNPinfo software.TaqMan probes were used for genotyping.A multiple logistic regression model was used to evaluate the effects of different SNP loci on the risk of neuroblastoma.The expression of ALKBH5 in neuroblastoma was evaluated by Western blotting and immunohistochemistry(IHC).Cell counting kit-8(CCK-8),plate colony formation and 5-ethynyl-2'-deoxyuridine(EdU)incorporation assays were used to evaluate cell proliferation.Wound healing and Transwell assays were used to compare cell migration and invasion.Thermodynamic modelling was performed to predict the ability of miRNAs to bind to ALKBH5 with the rs8400 G/A polymorphism.RNA sequencing,N6-methyladenosine(mA)sequencing,mA methylated RNA immunoprecipitation(MeRIP)and a luciferase assay were used to identify the targeting effect of ALKBH5 on SPP1.Results:ALKBH5 was highly expressed in neuroblastoma.Knocking down ALKBH5 inhibited the proliferation,migration and invasion of cancer cells.miR-186-3p negatively regulates the expression of ALKBH5,and this ability is affected by the rs8400 polymorphism.When the G nucleotide was mutated to A,the ability of miR-186-3p to bind to the 3'-UTR of ALKBH5 decreased,resulting in upregulation of ALKBH5.SPPI is the downstream target gene of the ALKBH5 oncogene.Knocking down SPP1 partially restored the inhibitory effect of ALKBH5 downregulation on neuroblastoma.Downregulation of ALKBH5 can improve the therapeutic efficacy of carboplatin and etoposide in neuroblastoma.Conclusions:We first found that the rs8400 G>A polymorphism in the m6A demethylase-encoding gene ALKBH5 increases neuroblastoma susceptibility and determines the related mechanisms.The aberrant regulation of ALKBH5 by miR-186-3p caused by this genetic variation in ALKBH5 promotes the occurrence and development of neuroblastoma through the ALKBH5-SPP1 axis.

Air-Stable Binary Hydrated Eutectic Electrolytes with Unique Solvation Structure for Rechargeable Aluminum-Ion Batteries

Aluminum-ion batteries(AIBs)have been highlighted as a potential alternative to lithium-ion batteries for large-scale energy storage due to the abundant reserve,light weight,low cost,and good safety of Al.However,the development of AIBs faces challenges due to the usage of AlCl_(3)-based ionic liquid electrolytes,which are expensive,corrosive,and sensitive to humidity.Here,we develop a low-cost,non-corrosive,and air-stable hydrated eutectic electrolyte composed of aluminum perchlorate nonahydrate and methylurea(MU)ligand.Through optimizing the molar ratio to achieve the unique solvation structure,the formed Al(ClO_4)_(3)·9H_(2)O/MU hydrated deep eutectic electrolyte(AMHEE)with an average coordination number of 2.4 can facilely realize stable and reversible deposition/stripping of Al.When combining with vanadium oxide nanorods positive electrode,the Al-ion full battery delivers a high discharge capacity of 320 mAh g^(-1)with good capacity retention.The unique solvation structure with a low desolvation energy of the AMHEE enables Al^(3+)insertion/extraction during charge/discharge processes,which is evidenced by in situ synchrotron radiation X-ray diffraction.This work opens a new pathway of developing low-cost,safe,environmentally friendly and high-performance electrolytes for practical and sustainable AIBs.

H_(2)S-mediated balance regulation of stomatal and non-stomatal factors responding to drought stress in Chinese cabbage

Increased evidence has shown that hydrogen sulfide(H_(2)S),a novel gasotransmitter,could enhance drought resistance in plants by inducing stomatal closure,with concurrent enhancement of photosynthetic efficiency,but little is known about the mechanism behind this contradictory phenomenon.This study examined the regulating mechanism of H_(2)S in response to drought stress fromstomatal and non-stomatal factors in Chinese cabbage.The results showed that exogenous H_(2)S could increase the accumulation of photosynthetic pigments and alleviate the damage caused by drought stress.It also regulated the expression in transcriptional level and the activity of ribulose 1,5-bisphosphate carboxylase/oxygenase(BrRuBisCO)under drought stress.The large subunit of BrRuBisCO was found to be modified by S-sulfhydration,which might be the reason for its increased enzyme activity.The fluxes of Cl^(−),K^(+),and H^(+)in the guard cells were detected by non-invasive micro-test techniques while under drought stress.The results indicated that H_(2)S signaling induced a transmembrane Cl^(−)and H^(+)efflux and inhibited K^(+)influx,and the Cl^(−)channel was the main responders for H_(2)S-regulated stomatal movement.In conclusion,H_(2)S signal not only activated the ion channel proteins located in the guard cell membrane to induce stomatal closure,but also regulated the transcriptional expression and the activity of RuBisCO,a non-stomatal factor to enhance the photosynthetic efficiency of leaves.There is therefore a beneficial balance between the regulation of H_(2)S signaling on stomatal factors and non-stomatal factors due to drought stress,which needs to be better understood to apply it practically to increase crop yields.

EPAS1 prevents telomeric damage-induced senescence by enhancing transcription of TRF1,TRF2,and RAD50

Telomeres are nucleoprotein structures located at the end of each chromosome,which function in terminal protection and genomic stability.Telomeric damage is closely related to replicative senescence in vitro and physical aging in vivo.As relatively long-lived mammals based on body size,bats display unique telomeric patterns,including the upregulation of genes involved in alternative lengthening of telomeres(ALT),DNA repair,and DNA replication.At present,however,the relevant molecular mechanisms remain unclear.In this study,we performed cross-species comparison and identified EPAS1,a well-defined oxygen response gene,as a key telomeric protector in bat fibroblasts.Bat fibroblasts showed high expression of EPAS1,which enhanced the transcription of shelterin components TRF1 and TRF2,as well as DNA repair factor RAD50,conferring bat fibroblasts with resistance to senescence during long-term consecutive expansion.Based on a human single-cell transcriptome atlas,we found that EPAS1 was predominantly expressed in the human pulmonary endothelial cell subpopulation.Using in vitro-cultured human pulmonary endothelial cells,we confirmed the functional and mechanistic conservation of EPAS1 in telomeric protection between bats and humans.In addition,the EPAS1 agonist M1001 was shown to be a protective compound against bleomycin-induced pulmonary telomeric damage and senescence.In conclusion,we identified a potential mechanism for regulating telomere stability in human pulmonary diseases associated with aging,drawing insights from the longevity of bats.

Membranous nephropathy with systemic light-chain amyloidosis of remission after rituximab therapy:A case report

BACKGROUND About 70%-80%of patients with primary membranous nephropathy(MN)have phospholipase A2 receptor(PLA2R)in renal tissue.Systemic light-chain(AL)amyloidosis is the most common type of amyloidosis.MN complicated with amyloidosis is rare.CASE SUMMARY A 48-year-old Chinese male presented with nephrotic syndrome,positive serum PLA2R antibody,and positive serum and urine IgG-lambda type M-protein,with a normal ratio of serum-free light-chain level.The patient was diagnosed with MN accompanied by AL amyloidosis.He was treated with rituximab with glucocorticoids and CyBorD regimen of chemotherapy.After 21 mo of follow-up,the patient achieved complete remission regarding nephrotic syndrome without adverse effects of chemotherapy.CONCLUSION We report a case of PLA2R-related MN complicated with primary AL amyloidosis only with renal involvement and successfully treated with rituximab,glucocorticoids and chemotherapy.

Economic Influencing Factors of Trade Volume Between China and RCEP Member States

This paper examines the impact of key economic factors on trade volumes between China and the Regional Comprehensive Economic Partnership(RCEP)member states.Studies have shown that gross domestic products(GDP),exchange rate,and inflation have an impact on China’s import and export trade volume with RCEP member states.China’s export trade volume to RCEP member states is deeply affected by China’s GDP,but the import trade volume depends on China’s domestic demand and market.The impact of exchange rates on import and export trade volumes varies from country to country.China’s export volume to RCEP member states is generally more affected by the consumption level of its residents than the consumption level of Chinese residents.

紫檀芪抗肿瘤作用机制研究进展

紫檀芪(3,5-二甲氧基-4’-羟基二苯乙烯)是一种主要存在于蓝莓、葡萄和花榈木中的多酚类化合物。已有的研究发现紫檀芪具有抗肺癌、乳腺癌、胃癌、结肠癌等多种肿瘤的抗癌作用。其作用机制涉及调控影响多种肿瘤生物学特性。此外,紫檀芪具有比白藜芦醇更高的生物利用度和生物活性,其抗肿瘤作用和机制值得深入探讨和研究。

先天性鼻泪道阻塞治疗时机及方式选择

先天性鼻泪道阻塞(congenital nasolacrimal duct obstruction,CNLDO)是患儿最常见的眼部疾病之一,其主要特征是鼻泪道下端瓣膜闭塞。CNLDO现有治疗方法包括泪囊按摩、泪道探通术、硅胶管置入术、球囊扩张术、鼻腔泪囊吻合术。近来,联合使用泪道内窥镜,可提高手术成功率。由于疾病本身有自愈倾向,手术时机及治疗方案选择目前存在很多争议,本文就这一问题进行综述,以便为CNLDO治疗提供参考方案。

Alginate oligosaccharide-induced intestinal morphology, barrier function and epithelium apoptosis modifications have beneficial effects on the growth performance of weaned pigs

Background: Alginate oligosaccharide(AOS), produced from alginate by alginate lyase-mediated depolymerisation, is a potential substitute for antibiotics and possesses growth-enhancing effects. Nevertheless, the mechanisms by which AOS regulates porcine growth remain to be elucidated. Therefore, we investigated the AOS-mediated changes in the growth performance of weaned pigs by determining the intestinal morphology, barrier function,as well as epithelium apoptosis.Methods: Twenty-four weaned pigs were distributed into two groups(n = 12) and received either a basal diet(control group) or the same diet supplemented with 100 mg/kg AOS. On d 15, D-xylose(0.1 g/kg body weight)was orally administrated to eight randomly selected pigs per treatment, and their serum and intestinal mucosa samples were collected 1 h later.Results: Our results showed that inclusion of AOS in the diet for 2 wk increased(P < 0.05) the average daily body weight gain in weaned pigs. Notably, AOS supplementation ameliorated the intestinal morphology and barrier function, as suggested by the enhanced(P < 0.05) intestinal villus height, secretory immunoglobulin A content and goblet cell counts. Compared to the control group, AOS ingestion both decreased(P < 0.05) the total apoptotic percentage and increased(P < 0.05) the proportion of S phase in the intestinal epithelial cells. Furthermore, AOS not only up-regulated(P < 0.05) the B-cell lymphoma-2(BCL2) transcriptional level but also down-regulated(P < 0.05) the B-cell lymphoma-2-associated X protein(BAX), cysteinyl aspartate-specific proteinase-3(caspase-3) and caspase-9 transcriptional levels in the small intestine.Conclusions: In summary, this study provides evidence that supplemental AOS beneficially affects the growth performance of weaned pigs, which may result from the improved intestinal morphology and barrier function,as well as the inhibited enterocyte death, through reducing apoptosis via mitochondria-dependent apoptosis.

Identification of a five-long non-coding RNA signature to improve the prognosis prediction for patients with hepatocellular carcinoma

AIM To construct a long non-coding RNA(lnc RNA) signature for predicting hepatocellular carcinoma(HCC) prognosis with high efficiency.METHODS Differentially expressed lnc RNAs(DELs) between HCC specimens and peritumor liver specimens were identified using the edge R package to analyze The Cancer Genome Atlas(TCGA) LIHC dataset.Univariate Cox proportional hazards regression was performed to obtain the DELs significantly associated with overall survival(OS) in a training set.These OS-related DELs were further analyzed using a stepwise multivariate Cox regression model.Those lnc RNAs fitted in the multivariate Cox regression model and independently associated with overall survival were chosen to build a prognostic risk formula.The prognostic value ofthis formula was then validated in the test group and the entire cohort and further compared with two previously identified prognostic signatures for HCC.Gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses were performed to explore the potential biological functions of the lnc RNAs in the signature.RESULTS Based on lnc RNA expression profiling of 370 HCC patients from the TCGA database,we constructed a 5-lnc RNA signature(AC015908.3,AC091057.3,TMCC1-AS1,DCST1-AS1 and FOXD2-AS1) that was significantly associated with prognosis.HCC patients with high-risk scores based on the expression of the 5 lnc RNAs had significantly shorter survival times compared to patients with low-risk scores in both the training and test groups.Multivariate Cox regression analysis demonstrated that the prognostic value of the 5 lnc RNAs was independent of clinicopathological parameters.A comparison study involving two previously identified prognostic signatures for HCC demonstrated that this 5-lnc RNA signature showed improved prognostic power compared with the other two signatures.Functional enrichment analysis indicated that the 5 lnc RNAs were potentially involved in metabolic processes,fibrinolysis and complement activation.CONCLUSION Our present study constructed a 5-lnc RNA signature that improves survival prediction and can be used as a prognostic biomarker for HCC patients.

Large-Scale Membrane Bioreactors for Industrial Wastewater Treatment in China:Technical and Economic Features,Driving Forces,and Perspectives

Membrane bioreactors(MBRs)have been and will continue playing an important role in industrial wastewater treatment and reuse in China.The sustainable development of MBR technology in its mature-application stage requires reciprocal interactions between engineering and research participants.Thus,in this study,a total of 182 large-scale MBR projects treating industrial wastewater(with individual treatment capacities5000 m3d1)commissioned and under construction from 2003 to 2019 were analyzed comprehensively.Fast growth of the cumulative treatment capacity was observed,with extension to diverse industries,and the super large-scale was enhanced recently.The treatment processes,pollutant removal efficiencies,and actual operational parameters were summarized regarding the particularity of industrial wastewater compared to municipal wastewater.Economic features including the total investment costs of the projects,their total footprint,and their operational energy consumption were analyzed as well.A vigorous MBR market has formed in China with the fast development of membrane elements and engineering suppliers,continuously increasing official oriented projects,and responsive and innovative business modes.MBR technology has been mostly applied in specific economic zones and water-deficient areas,but its widespread use all over China is foreseeable considering the vast future market for industrial wastewater treatment and recycling.The policy–economy and market–technology driving forces revealed that MBR is consistent with the national development demand.According to the survey and analysis,prospective development in both engineering and research aspects of MBR is proposed to maintain its competitive edge.

Effect of Point-of-care Hemoglobin/Hematocrit Devices and Autologous Blood Salvage on Reduction of Perioperative Allogeneic Blood Transfusion

Objective To evaluate the effect of point-of-care hemoglobin/hematocrit(POC HGB/HCT) devices and intraoperative blood salvage on the amount of perioperative allogeneic blood transfusion and blood conservation in clinical practice. Methods A total of 46 378 medical records of 22 selected hospitals were reviewed. The volume of allogeneic red blood cell and plasma, number of patients transfused, number of intraoperative autologous blood salvage, total volume of autologous blood transfusion, and amount of surgery in the year of 2011 and 2013 were tracked. Paired t-test was used in intra-group comparison, while t-test of two isolated samples carried out in inter-group comparison. P<0.05 was defined as statistically significant difference. Results In the hospitals where POC HGB/HCT device was used(n=9), the average allogeneic blood transfusion volume per 100 surgical cases in 2013 was significantly lower than that in 2011(39.86±20.20 vs. 30.49±17.50 Units, t=3.522, P=0.008). In the hospitals without POC HGB/HCT meter, the index was not significantly different between 2013 and 2011. The average allogeneic blood transfusion volume was significantly reduced in 2013 than in 2011 in the hospitals where intraoperative autologous blood salvage ratio [autologous transfusion volume/(autologous transfusion volume+allogeneic transfusion volume)] was increased(n=12, t=2.290, P=0.042). No significant difference of the above index was found in the hospitals whose autologous transfusion ratio did not grow. Conclusion Intraoperative usage of POC HGB/HCT devices and increasing autologous transfusion ratio could reduce perioperative allogeneic blood transfusion.

外电场作用下离子液体振动光谱变化的分子动力学模拟研究

振动光谱学是研究液体分子微观结构的强有力工具,利用振动光谱学探究外界条件作用下液体结构性质的变化是可行的。本文利用分子动力学模拟方法研究了从0到10 V·nm^(−1)变化的外加电场对1-乙基-3-甲基咪唑六氟磷酸盐离子液体的振动光谱的影响,并且详细分析了位于50,183,3196,3396 cm^(−1)的振动峰的强度及位置随外加电场变化而变化的内在原因。随着外加电场从0增大到10 V·nm^(−1),由于模拟体系中平均每对阴阳离子的总偶极矩增大(从4.34到5.46 Debye)和阳离子的取向更加一致,使得位于50、183 cm^(−1)的振动峰的强度相应地逐渐增强。位于3196 cm^(−1)的振动峰的强度明显减弱,因为外加电场的作用使甲基和乙基侧链上碳原子周围的氢原子不断增多,从而使烷基链上碳氢键的伸缩振动受限。外加电场作用下分子间+C―H···F−氢键的减少使位于3396 cm^(−1)的振动峰的强度逐渐减弱。而位于50和3396 cm^(−1)的振动峰的红移现象分别归因于每对离子平均相互作用能的减小(从−378.7到−298.0 kJ·mol^(−1))和有利于氢键结合的弛豫效应。

子宫输卵管超声重复造影评价输卵管通畅性的临床价值

目的分析重复四维子宫输卵管超声造影在评价输卵管通畅性的可行性及临床价值。方法选取2015年1月—2018年7月于青岛市市立医院行四维子宫输卵管超声造影检查,且结果显示单侧或双侧输卵管完全阻塞的140例患者作为研究对象。按照自愿原则分为单次造影组和重复造影组,比较两组检查结果与腹腔镜检查结果的一致性,分析重复造影与单次造影结果不一致患者的临床资料,比较两组患者的不良反应情况。结果单次造影组、重复造影组与腹腔镜检查结果的符合率分别为87.9%和95.2%,单次造影组的Kappa值为0.760,与腹腔镜检查结果的一致性良好,重复造影组的Kappa值为0.905,与腹腔镜检查结果的一致性很好。结果不一致组的子宫水平位及输卵管远端阻塞的比例、置管深度/内膜线长度、球囊注水量较结果一致组高(P<0.05)。重复造影组NRS疼痛评分较单次造影组高(P<0.05)。结论四维子宫输卵管超声造影检查显示单侧或双侧阻塞患者可行重复造影检查,以提高造影结果的准确性。