Tunable Shape Memory Polyurethane Networks Cross-Linked by 1,3,5,7-Tetrahydroxyadamantane

Shuqin Fu,Jiaping Zhu,Shaojun Chen 한국고분자학회 2018 Macromolecular Research Vol.26 No.11

As a new type of smart polymers, the shape memory polyurethanes attract increasing attention because of their wide use in various applications. Herein, a serials of novel thermo-responsive shape memory polyurethane networks were developed by chemical cross-linking of polycaprolactone with 1,3,5,7-tetrahydroxyadamantane. The polyurethane networks were characterized in relation to their microstructure, cross-linking density, surface appearance, thermal properties, static and dynamic mechanical properties, and shape memory behavior. It was found that the prepared polyurethane networks can exhibit excellent thermo-responsive shape memory properties at body temperature by controlling the molar ratio of 1,3,5,7- tetrahydroxyadamantane and polycaprolactone. Moreover, the incorporation of 1,3,5,7-tetrahydroxyadamantane substantially improved the mechanical properties of the final polyurethane networks. The versatility of the synthesized polyurethane networks is reflected by its dual- and triple-shape memory performance. It can be anticipated that the synthesized polyurethane networks could be used as smart materials for applications involving shape memory polymers.

A NEW "MIDDLE" CRETACEOUS ZALAMBDALESTID MAMMAL, FROM A NEW LOCALITY IN JILIN PROVINCE, NORTHEASTERN CHINA

Shuqin Zan,Craig B. Wood,Guillermo W. Rougier,Liyong Jin,Jun Chen,Charles R. Schaff 한국고생물학회 2006 고생물학회지 Vol.22 No.1

중국 길림성의 Gongzhuling 시 근처의 새로운 백악기 화석지에서 산출된 화석은 두개의 불완전한 포유류 하악골을 포함하는데 이 표본은 태반류 Zalambdalestidae과에 속하는 새로운 속과 종이다. 화석지는 Songliao분지의 넓게 분포하는 Quantou층의 가창자리에 위치하는데 Songliao분지의 시대는 Aptian~Cenomanian으로 알려져 있다. 그러나 Quantou층이 Cenomanian 보다 더 젊을 것 같지는 않다. 두 하악골은 크고 납작한 첫 번째 앞니를 갖고 있는데 Kulbeckia kulbecke같은 종과 비교해 보면 원시적이고 진화적인 특징들이 흥미롭게 섞여 있다. 예를 들면, Gongzhuling 표본은 5개의 앞어금니 (거의 완전한 어금니 형태의 앞어금니)와 단지 3개의 앞니, 그리고 한 개의 낮고 단 뿌리의 송곳니를 가진다. 5번째 앞어금니와 첫 번째 어금니의 trigonids는 상대적으로 눌리지 않고 열려있는 형태다. 이 화석지는 “중기” 백악기 척추화석들에 대한 새로운 정보를 확보할 중요한 장소로 알려지게 될 것이며 가까운 미래에 이곳에서 새로운 포유류, 공룡, 그리고 다른 표본들이 기재될 것이다. Fossil specimens from a new Cretaceous locality near Gongzhuling City in Jilin Province, China, include two incomplete mammalian dentaries which represent a new genus and species referable to the eutherian family Zalambdalestidae. The locality is in basin-margin outcrops of the Quantou Formation, which is widely spread in the subsurface of Songliao Basin and which has been assigned ages ranging from the Aptian to the Cenomanian stages of the Cretaceous; it seems unlikely that the Quantou Formation could be younger than Cenomanian. Both dentaries possess an enlarged, procumbent first incisor combined with an interesting mosaic of both plesiomorphic and derived dental characters compared to taxa such as Kulbeckia kulbecke. For example, the new Gongzhuling specimens appear to show five premolars (including an almost fully molariform ultimate premolar) combined with only three incisors and a low but single-rooted canine. The trigonids on p5 and m1 are relatively open and non-compressed. This locality is likely to emerge as an important source of new information on "middle" Cretaceous vertebrates as additional mammalian, dinosaurian, and other specimens are described from it in the near future.

Bounded matrices over regular rings

Shuqin Wang,Huanyin Chen 대한수학회 2006 대한수학회보 Vol.43 No.1

In this paper, we investigate bounded matrices over regular rings. We observe that every bounded matrix over a regular ring can be described by idempotent matrices and invertible matrices. Let $A,B\in M_n(R)$ be bounded matrices over a regular ring $R$. We prove that $(AB)^d=U(BA)^dU^{-1}$ for some $U\in GL_n(R)$.

The Suppression of Radio Interference in HF Radar

CHEN ZHIQUN,ZHAO SHUQIN,QUAN TAIFAN 대한전자공학회 1998 International Conference on Electronics, Informati Vol.1998 No.8

BOUNDED MATRICES OVER REGULAR RINGS

Wang Shuqin,Chen Huanyin Korean Mathematical Society 2006 대한수학회보 Vol.43 No.1

In this paper, we investigate bounded matrices over regular rings. We observe that every bounded matrix over a regular ring can be described by idempotent matrices and invertible matrices. Let A, $B{in}M_n(R)$ be bounded matrices over a regular ring R. We prove that $(AB)^d = U(BA)^dU^{-1}$ for some $U{\in}GL_n(R)$.

Low Carbon Scheduling with Iterative Ant Colony Algorithm

Peng Liang,WenSi Chen,MingQiang Luo,ShuQin Chen 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.5

This research considers a low carbon scheduling problem in unrelated parallel machines. To solve this problem, we first establish a low carbon scheduling mathematical model. Then an iterative ant optimization algorithm is presented. Furthermore, parameters of proposed iterative ant optimization algorithm are selected by Taguchi methods on generating test dataset. Finally, comparative experiments indicate the proposed iterative ant optimization algorithm has better performance on minimizing energy consumption as well as total tardiness.

Facile Preparation of Mechanical Reinforced and Biocompatible Silk Gels

Qiang Zhang,Guocong Han,Chen Lu,Qiusheng Wang,Xiufang Li,Zuwei Luo,Renchuan You,Shuqin Yan 한국섬유공학회 2019 Fibers and polymers Vol.20 No.4

Nontoxic and controllable way to fabricate silk fibroin (SF) gel with high mechanical properties is of critical important to biomaterial in tissue engineering. Electrochemically triggered electrophoretic migration and electric charge of the silk molecules both contributed to SF microspheres and electronic gel (e-gel) formation by sol-gel transition. In this study, a novel silk pH e-gel with higher mechanical property was prepared by combining low-voltage electric fields with isoelectric point (pI) adjustment. This green process was mild and friendly without chemical crosslinker. Compressive modulus of the silk pH e-gel was up to 70 MPa that was significantly higher than that of SF gelation spontaneously. Furthermore, analysis of molecule conformation of the silk pH-e-gel demonstrated that most of random coil structures transformed into α-helix and a little β-sheet structures during this process. The silk pH e-gel was loaded with rhodamine B and showed an obvious sustainable release profile. Accumulation releasing amounts was approximately 60 % at day 9. Cytocompatibility of the silk pH-e-gel was evaluated by epithelial cell. The results showed that the gels could support the cell growth and proliferation in vitro. Finally, gel biodegradation was assessed by protease XIV. After biodegradation for 28 days, remaining weight of the gel was about 20.23±2.59 wt%, indicating its good biodegradability. This novel process was established successfully by combining low voltage field with pH-control, which provided an alternative material for regenerative medicine.

Combination of High-Density Lipoprotein Cholesterol and Lipoprotein(a) as a Predictor of Collateral Circulation in Patients With Severe Unilateral Internal Carotid Artery Stenosis or Occlusion

Shuyin Ma,Meijuan Zhang,Huiyang Qu,Yuxuan Cheng,Shuang Du,Jiaxin Fan,Qingling Yao,Xiao Dong Zhang,Mengying Chen,Nan Zhang,Kaili Shi,Yizhou Huang,Shuqin Zhan 대한신경과학회 2022 Journal of Clinical Neurology Vol.18 No.1

Background and Purpose Collateral circulation is considered an important factor affecting the risk of stroke, but the factors that affect collateral circulation remain unclear. This study was performed to identify the factors associated with collateral circulation, especially blood lipids. Methods The study involved patients who had undergone digital subtraction angiography and were confirmed as having severe unilateral stenosis or occlusion of the internal carotid artery (ICA). We classified the collateral circulation status of each patient as good (Grade 3 or 4) or poor (Grade 0, 1, or 2) according to the grading system of the American Society of Interventional and Therapeutic Neuroradiology/American Society of Interventional Radiology. We collected data on patients’ characteristics and identified the factors that affect collateral circulation. Results This study included 212 patients. The multivariate logistic regression analysis showed that the high-density lipoprotein cholesterol (HDL-C) concentration and a complete anterior half of the circle of Willis were independent protective factors for good collateral circulation, whereas elevated lipoprotein(a) [Lp(a)] and serum creatinine concentrations were independent risk factors for good collateral circulation. The area under the receiver operating characteristics curve (AUC) was 0.68 (95% confidence interval [CI], 0.61–0.76) for HDL-C and 0.69 (95% CI, 0.62–0.76) for Lp(a). A binary logistic regression model analysis of the joint factor of HDL-C and Lp(a) yielded an AUC of 0.77 (95% CI, 0.71–0.84). Conclusions In patients with severe unilateral ICA stenosis or occlusion, the combination of HDL-C and Lp(a) is a useful predictor of collateral circulation.