Preparation of coated sand for selective laser sintering and optimization of baking process of sand moulds

A cold method was used to prepare coated sand for application in the selective laser sintering(SLS)process.Tensile strength,loss on ignition,gas evolution,and accuracy of the SLS samples were tested and analyzed,and the baking process was thoroughly investigated.Compared with coated sand prepared by the hot method,the cold method yields a more uniform and complete resin film on the sand's surface,resulting in enhanced tensile strength and accuracy.Additionally,the cold method requires a lower binder content to meet the same strength requirements,thereby minimizing gas evolution,reducing porosity defects,and ultimately improving casting quality.The coated sand samples prepared through the cold method exhibit superior accuracy,with a size error of within±0.4 mm.In contrast,the coated sand samples prepared by the hot method display a lower accuracy,with an average negative error of 2.1993 mm.The highest tensile strength could be attained by controlling the baking temperature within a suitable range(180-190°C),which can effectively reduce the generation of gas,thus contributing to improved overall performance.

Quantitative understanding of phase segregation behaviors by precisely building discrete oligo-ester-b-oligo-olefin block copolymers

Block copolymers(BCPs) with high Flory-Huggins parameter(χ) and balanced surface energy have aroused tremendous interest for ultra-small nanopatterns processing.However,high χ and balanced surface energy are generally contradicted.The fine tune of chain structure might be a useful way to achieve high χ and balanced surface energy.To realize this,the block copolymer with exactly uniform chain structure,i.e.,defined molecular structure,is highly desirable for accurately evaluating the phase behavior.Herein,two kinds of discrete oligo ester-b-oligo olefin block copolymers with different chemical structures(oligo lactic acid-boligo olefin BCP,oLA_(n)-b-C_(m);oligo phenyl lactic acid-b-oligo olefin BCP,oPL_(n)-b-C_(m)) were modularly synthesized through iterative growth methods.The effect of chain structure on segregation strength and surface properties was quantitatively investigated using the discrete BCPs as precise models.On the one hand,introducing rigid and nonpolar phenyl groups into oligo ester block has a negligible effect on the chemical incompatibility,as confirmed by the identical high χ values of oLA_(n)-b-C_(m) and oPL_(n)-b-C_(m)(χ_(oLA/C)=0.21 and χ_(oPL/C)=0.19).On the other hand,the incorporation of nonpolar phenyl groups creates balanced surface energy,that is,the high χ and balanced surface energy were simultaneously achieved by oPL_(n)-b-C_(m).Therefore,sub-10 nm perpendicular nanopatterns can be easily produced upon brief thermal treatment,demonstrating its potential application in semiconductor manufacturing with ultra-small feature size.The discrete BCP can serve as a quantitative and exquisite model to study the critical contribution of chain structures on phase separation behavior,providing insightful understanding to facilitate the potential application in the chip process.

Designer uniform Li plating/stripping through lithium–cobalt alloying hierarchical scaffolds for scalable high-performance lithium-metal anodes

Lithium metal anodes are of great interest for advanced high-energy density batteries such as lithiumair, lithium-sulfur and solid-state batteries, due to their low electrode potential and ultra-high theoretical capacity. There are, however, several challenges limiting their practical applications, which include low coulombic efficiency, the uncontrollable growth of dendrites and poor rate capability. Here, a rational design of 3D structured lithium metal anodes comprising of in-situ growth of cobalt-decorated nitrogen-doped carbon nanotubes on continuous carbon nanofibers is demonstrated via electrospinning.The porous and free-standing scaffold can enhance the tolerance to stresses resulting from the intrinsic volume change during Li plating/stripping, delivering a significant boost in both charge/discharge rates and stable cycling performance. A binary Co-Li alloying phase was generated at the initial discharge process, creating more active sites for the Li nucleation and uniform deposition. Characterization and density functional theory calculations show that the conductive and uniformly distributed cobalt-decorated carbon nanotubes with hierarchical structure can effectively reduce the local current density and more easily absorb Li atoms, leading to more uniform Li nucleation during plating. The current work presents an advance on scalable and cost-effective strategies for novel electrode materials with 3D hierarchical microstructures and mechanical flexibility for lithium metal anodes.

Leclercia adecarboxylata infective endocarditis in a man with mitral stenosis:A case report and review of the literature

BACKGROUND Infective endocarditis(IE) is a rare disease with a high mortality rate.Leclercia adecarboxylata(L.adecarboxylata) is a movable Gram-negative bacillus of enterobacteriaceae,and it can rarely be a pathogen which often affects immunodeficient patients.There are about three cases of immunocompetent patients with monomicrobial L.adecarboxylata infection.There are only three reported cases of IE caused by L.adecarboxylata in the world.The mitral valve is often affected in IE,and the prognosis for IE with mitral valve lesions is often poor.CASE SUMMARY A 51-year-old man was found to have moderate to severe mitral stenosis on echocardiography.He came to our Cardiothoracic Surgery Department for surgical management.A diastolic murmur was heard on auscultation of the heart in the mitral region.On the second day of hospitalisation,he presented with slurred speech,reduced muscle strength in the left limb,and acute cerebral infarction on cranial computed tomography.Surgical treatment was decided to postpone.On the ninth day of admission,the patient developed a sudden high fever and shock and was transferred to the Cardiac Intensive Care Unit,where echocardiogram revealed an anterior mitral valve leaflet vegetation.After empirical anti-infective treatment with vancomycin(1g q12h),an emergency valve replacement was performed.Bacterial culture identified L.adecarboxylata.Antiinfective treatment with piperacillin-tazobactam(4.5g q8h) was added for 4 wk.Follow-up echocardiography showed normal bioprosthetic valve function after mitral valve replacement.CONCLUSION We report the first case of L.adecarboxylata IE in China,and clinicians should pay attention to this pathogen.

Effect of gel time of 3D sand printing binder system on quality of sand mold/core

Two important factors affecting the performance of sand mold/core generated by 3D printing(3DP)are strength and dimensional accuracy,which are not only closely related to the reactivity of furan resin and the phase transition of silica sand,but also the curing agent system of furan resin.This paper studies the influence of gel time on the strength and dimensional accuracy of a 3DP sand mold/core,taking the furan resin system as an example and using a sand specimen generated by a 3DP inkjet molding machine.The experiment demonstrates that the gel time of 3 to 6 min for the sand mixture suits 3DP core-making most under the experimental condition.However,it should be noted that under the same resin condition,the strength of a no-bake sand mold/core is higher than that of a 3DP sand mold/core.The dimensional accuracy of the sand mold/core does not change significantly when the gel time is less than 15 min.Improving the activity of binder and developing ultra-strong acid with low corrosion shall be an effective way to improve the quality of the mold/core by 3D printing.

单一分子量含氟嵌段共聚物的本体及薄膜自组装研究

嵌段共聚物导向自组装作为一种自下而上的图案化工艺,受到工业界和学术界的广泛关注.然而,导向自组装中缺陷率与分子参数之间的关系研究尚不清晰.本文工作基于模块化合成策略,利用迭代指数增长法并结合巯基-双键的点击反应成功制备了高χ低N的单一分子量含氟聚酯嵌段共聚物(oLAn-FPOSS).单一分子量特征可以排除多分散性对自组装行为的影响.本体自组装研究表明聚酯嵌段和含氟嵌段具有强相分离驱动力,可以形成特征尺寸小于10 nm的六方柱状相结构(HEX).在薄膜自组装中,嵌段共聚物经过简单的热退火可以在硅片表面形成平行基底排布的柱状纳米图案.此外,通过对比研究不同链长单一分子量嵌段共聚物的薄膜组装行为,发现随着嵌段共聚物链长的增长薄膜组装图形缺陷率明显下降,初步揭示了薄膜自组装过程中缺陷形成对嵌段共聚物链长的依赖性.

单一分子量γ-丁内酯齐聚物的合成及其结晶行为研究

聚γ-丁内酯作为一种真正意义上可以实现“单体—聚合物—单体”的可循环聚酯种类,其结构性能的精准研究引起了广泛的兴趣.本文从生物基原料丁内酯和丁二酸酐出发,通过迭代指数级增长策略结合高效的酯化条件,合成了一系列单一分子量γ-丁内酯齐聚物,其结构经过了核磁共振氢谱,凝胶渗透色谱和大分子质谱的严格表征,并研究了这些单一分子量γ-丁内酯齐聚物的结晶行为.结果表明,单一分子量γ-丁内酯齐聚物的熔融温度随分子量的增加而升高,而多分散样品的熔融温度与分子量近似的单一分子量γ-丁内酯齐聚物相似.在相同结晶温度下,分子量越高,成核速率和球晶生长速率越大,结晶越快.多分散样品的结晶行为主要受高分子量组分的影响.

A carbazole-hemicyanine dye based ratiometric fluorescent probe for selective detection of bisulfite(HSO_3^-)in cells and C. elegans

Bisulfite(HSO_3) is an important sulfur dioxide(SO_2) derivative, which plays a major role in many physiological processes and is also closely associated with a variety of diseases. Thus the development of highly selective and sensitive fluorescent probes is essential to detect HSO_3 in living cells. In this work,we report the synthesis and analysis of a ratiometric fluorescent probe for selective detection of HSO_3 based on the 1,4-nucleophilic addition reaction with the carbazole as an electron donor(D) and aldehyde group as an electron acceptor(A). The addition of HSO_3 and other ions to our probe can be observed by UV vis and fluorescence spectrometry. Our investigation proved that the probe is highly selective and sensitive for HSO_3 and ratiometric changes. Moreover, the probe has good cell permeability and was successfully applied to the detection of exogenous HSO_3 in Hela cells and C. elegans.

胰岛素粉末无针注射的给药效率和皮肤刺激性评价(英文)

研究目的:胰岛素在临床上广泛用于糖尿病的治疗,但需要注射方式给药,给患者带来不便。本文报道了一种胰岛素粉末无针注射给药的新方法,并对其给药效率和皮肤刺激性进行评价。创新要点:首次报道了胰岛素粉末无针注射给药方法,有望为糖尿病患者长期自我给药提供便捷。研究方法:自主设计便携式自动无针粉末注射给药装置,采用计算机辅助方法计算给药装置的主要空气动力学参数;采用家兔评价无针粉末注射对皮肤的刺激性,并分析与空气动力学参数的相关性;采用四氧嘧啶诱导家兔糖尿病模型,评价不同无机盐载药的胰岛素粉末的无针注射给药降糖效果。重要结论:采用自主设计便携式自动无针粉末注射给药装置,递送以无机盐为载体的胰岛素粉末具有显著的降血糖作用,而递送胰岛素原料药粉末无降血糖作用,说明无机盐载体对胰岛素粉末无针注射给药效果具有重要作用。皮肤刺激性实验表明,储气室气压、容积以及喷管与皮肤的间距三个参数显著影响无针粉末注射装置的皮肤损伤程度,优化后的注射条件对皮肤几乎没有损伤。优化给药条件下以磷酸盐载体的胰岛素粉末无针注射给药,相对给药效率为72.25%。研究结果表明无针粉末注射技术用于胰岛素或其它生物制品的无针给药具有良好应用前景。

A Rhodamine-based fluorescent sensor for chromium ions and its application in bioimaging

A rhodamine-based sensor（1） has been developed for the detection of chromium ions.Cr-（3＋）-induced opening of the rhodamine spirocycle in sensor（1） led to the distinct colorimetric and fluorescence responses.Among all the tested ions,only Cr-（3＋） generated a significant fluorescence enhancement of up to13-fold,which indicated the high selectivity of 1.Sensor（1） was successfully applied in the in vivo fluorescence imaging of Cr-（3＋） in C.elegans.The results provided solid evidences for the future estimation of Cr-（3＋） in environmental applications and tobacco samples.

MCU-induced mitochondrial calcium uptake promotes mitochondrial biogenesis and colorectal cancer growth

Mitochondrial calcium uniporter(MCU)has an important role in regulating mitochondrial calcium(Ca^(2+))homeostasis.Dysregulation of mitochondrial Ca^(2+)homeostasis has been implicated in various cancers.However,it remains unclear whether MCU regulates mitochondrial Ca^(2+)uptake to promote cell growth in colorectal cancer(CRC).Therefore,in the present study the expression of MCU in CRC tissues and its clinical significance were examined.Following which,the biological function of MCUmediated mitochondrial Ca^(2+)uptake in CRC cell growth and the underlying mechanisms were systematically evaluated using in in vitro and in vivo assays,which included western blotting,cell viability and apoptosis assays,as well as xenograft nude mice models.Our results demonstrated that MCU was markedly upregulated in CRC tissues at both the mRNA and protein levels.Upregulated MCU was associated with poor prognosis in patients with CRC.Our data reported that upregulation of MCU enhanced the mitochondrial Ca^(2+)uptake to promote mitochondrial biogenesis,which in turn facilitated CRC cell growth in vitro and in vivo.In terms of the underlying mechanism,it was identified that MCU-mediated mitochondrial Ca^(2+)uptake inhibited the phosphorylation of transcription factor A,mitochondrial(TFAM),and thus enhanced its stability to promote mitochondrial biogenesis.Furthermore,our data indicated that increased mitochondrial Ca^(2+)uptake led to increased mitochondrial production of ROS via the upregulation of mitochondrial biogenesis,which subsequently activated NF-κB signaling to accelerate CRC growth.In conclusion,the results indicated that MCU-induced mitochondrial Ca^(2+)uptake promotes mitochondrial biogenesis by suppressing phosphorylation of TFAM,thus contributing to CRC cell growth.Our findings reveal a novel mechanism underlying mitochondrial Ca^(2+)-mediated CRC cell growth and may provide a potential pharmacological target for CRC treatment.

Regulatory variation within 3’UTR of STAT5A correlates with sudden cardiac death in Chinese populations

Definitive diagnosis to sudden cardiac death(SCD)is often challenging since the postmortem examination on SCD victims could hardly demonstrate an adequate cause of death.It is therefore important to uncover the inherited risk component to SCD.Signal transducer and activators of transcription 5 A(STAT5A)is a member of the STAT family and a transcription factor that is activated by many cell ligands and associated with various cardiovascular processes.In this study,we performed a systematic variant screening on the STAT5A to filter potential functional genetic variations.Based on the screening results,an insertion/deletion polymorphism(rs3833144)in 3’UTR of STAT5A was selected as the candidate variant.A total of 159 SCD cases and 668 SCD matched healthy controls was enrolled to perform a case-control study and evaluate the association between rs3833144 and SCD susceptibility in Chinese populations.Logistic regression analysis showed that the deletion allele of rs3833144 had significantly increased the SCD risk(odds ratio(OR)=1.54;95%confidence interval(CI)=1.18-2.01;P=0.000955).Further genotype-expression eQTL analysis showed that samples with deletion allele appeared to lower expression of STAT5A,and in silico prediction suggested the local 3 D structure changes of STAT5A mRNA caused by the variant.On the other hand,the bioinformatic analysis presented that promoters of RARA and PTGES3L-AARSD1 could interact with rs3833144,and eQTL analysis showed the higher expression of both genes in samples with deletion allele.Dual-luciferase activity assays also suggested the significant regulatory role of rs3833144 in gene transcription.Our current data thus suggested a possible involvement of rs3833144 to SCD predisposition in Chinese populations and rs3833144 with potential function roles may become a candidate marker for SCD diagnosis and prevention.

Developmental validation of the novel six-dye Goldeneye^(TM)DNA ID System 35InDel kit for forensic application

Insertion/deletion polymorphisms(InDels)have been treated as a prospective and helpful genetic marker in the fields of forensic human identification,anthropology and population genetics for the past few years.In this study,we developed a six-dye multiplex typing system consisting of 34 autosomal InDels and Amelogenin for forensic application.The contained InDels were specifically selected for Chinese population with the MAF≥0.25 in East Asia,which do not overlap with the markers of Investigator^(■)DIPplex kit.The typing system was named as GoldeneyeTM DNA ID System 35InDel Kit,and a series of developmental validation studies including repeatability/reproducibility,concordance,accuracy,sensitivity,stability,species specificity and population genetics were conducted on this kit.We confirmed that the 35InDel kit is precise,sensitive,species specific and robust for forensic practice.Moreover,the 35InDel kit is capable of typing DNA extracted from forensic routine case-type samples as well as degraded samples and mixture samples.All markers are proved to be highly polymorphic with an average observed heterozygosity(He)of 0.4582.The combined power of discrimination(CPD)is 0.999999999999978 and the combined power of exclusion in duos(CPE_(D))and trios(CPE_(T))are 0.978837 and 0.999573,respectively,which are higher than those of the Investigator^(■)DIPplex kit.Thus,the GoldeneyeTM DNA ID System 35InDel kit is suitable for forensic human identification and could serve as a supplementary typing system for paternity testing.

Beneficial Effect of Berberis amurensis Rupr. on Penile Erection

Objective： To investigate whether the methanol extract of Berberis amurensis Rupr. （BAR） augments penile erection using in vitro and in vivo experiments. Methods： The ex vivo study used corpus cavemosum strips prepared from adult male New Zealand White rabbits. In in vivo studies for intracavernous pressure （ICP）, blood pressure, mean arterial pressure （MAP）, and increase of peak ICP were continuously monitored during electrical stimulation of Sprague-Dawley rats. Results： Preconstricted with phenylephrine （PE） in isolated endothelium- intact rabbit corus cavernosum, BAR relaxed penile smooth muscle in a dose-dependent manner, which was inhibited by pretreatment with NG-nitro-L-arginine methyl ester （L-NAME）, a nitric oxide synthase inhibitor, and 1H-[1,2,4]-oxadiazole-[4,3-α]-quinoxalin-l-one, a soluble guanylyl cclase inhibitor. BAR significantly relaxed penile smooth muscles dose-dependently in ex vivo, and this was inhibited by pretreatment with L-NAME 1H-[1,2,4]- oxadiazole-[4,3-α ]-quinoxalin-l-one. BAR-induced relaxation was significantly attenuated by pretreatment with tetraethylammonium （TEA, P〈0.01）, a nonselective K＋ channel blocker, 4-aminopyridine （4-AP, P〈0.01）, a voltage-dependent K＋ channel blocker, and charybdotoxin （P〈0.01）, a large and intermediate conductance Ca2. sensitive-K＋ channel blocker, respectively. BAR induced an increase in peak ICP, ICP/MAP ratio and area under the curve dose dependently. Conclusion： BAR augments penile erection via the nitric oxide/cyclic guanosine monophosphate system and Ca2. sensitive-K＋ （BK＋ and IK＋） channels in the corpus cavemosum.