Use of Thixoforming as a Manufacturing Method for Metallic Composites

Hüsnügül Yilmaz Atay,David Aišman,Hana Jirková,Mária Behulova,Bohuslav Mašek 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.9

Thixoforming is one of the members of the family of semi-solid forming processes. It is possible to obtain complex shapeof materials by this method and unconventional microstructures can be achieved due to its thixotropic properties. However,in this study thixoforming was used not only as forming method but also as a manufacturing method. Metallic compositeswere manufactured by a process of integration of powder metallurgy and semi-solid production technique. The mixture ofCo72.5B15Si12.5alloy and Fe powders become partially melted, compressed mechanically in semi-solid state and filled intricatecavities. Without changing alloy structure, it could be possible to reinforce it with Fe powders. Moreover, the final shapeof the product could be achieved at the same time. Prior to the process, Co72.5B15Si12.5alloy obtained in the form of stickwas characterized by X-ray diffraction (XRD), scanning electron microscopy–energy dispersive spectroscopy (SEM–EDX),differential thermal analysis-thermogravimetry (DTA-TG), light microscope and micro-hardness machine. The stick wasmilled to get alloy powders and they were blended with iron. Characterization of the structures of the composite materialwas performed. It was concluded that the heating process of iron and alloy powders provides the formation of compact metalmatrix composites.

Novel Cationic 2-Phenylpyridine-based Iridium(III) Complexes Bearing an Ancillary Phosphine Ligand: Synthesis, Photophysics and Crystal Structure

Ma, Ai-Feng,Seo, Hoe-Joo,Jin, Sung-Ho,Yoon, Ung-Chan,Hyun, Myeong-Ho,Kang, Sung-Kwon,Kim, Young-Inn Korean Chemical Society 2009 Bulletin of the Korean Chemical Society Vol.30 No.11

Three novel phosphorescent 2-phenylpyridine-based iridium(III) complexes, $[(ppy)_2Ir(P\^{}N)]PF6\;(1),\;[(dfppy)_2Ir(P\^{}N)]PF_6$ (2), and $[(dfmppy)_2 Ir(P\^{}N)]PF6$ (3), where $P\^{}N$ = 2-[(diphenylphosphino)methyl]pyridine (dppmp), were synthesized and characterized. The absorption, photoluminescence, cyclic voltammetry and thermal stability of the complexes were investigated. The complexes showed bright blue luminescences at wavelengths of 448 $\sim$ 500 nm at room temperature in $CHCl_3$ and revealed that the $\pi$-acceptor ability of the phosphorous atom in the ancillary dppmp ligand plays an important role in tuning emission color resulting in a blue-shift emission. The single crystal structure of $[(dfmppy))_2Ir(P\^N)]PF_6$ was determined using X-ray crystallography. The iridium metal center adopts a distorted octahedral structure coordinated to two dfmppy and one dppmp ligand, showing cis C-C and trans N-N chelate dispositions. There is a $\pi-\pi$ overlap between π electrons delocalized in the difluorophenyl rings.

Novel Cationic 2-Phenylpyridine-based Iridium(III) Complexes Bearing an Ancillary Phosphine Ligand: Synthesis, Photophysics and Crystal Structure

Ai-Feng Ma,Hoe-Joo Seo,진성호,윤웅찬,현명호,강성권,김영인 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.11

Three novel phosphorescent 2-phenylpyridine-based iridium(III) complexes, [(ppy)2Ir(P^N)]PF6 (1), [(dfppy)2Ir(P^N)] PF6 (2), and [(dfmppy)2 Ir(P^N)]PF6 (3), where P^N = 2-[(diphenylphosphino)methyl]pyridine (dppmp), were synthesized and characterized. The absorption, photoluminescence, cyclic voltammetry and thermal stability of the complexes were investigated. The complexes showed bright blue luminescences at wavelengths of 448 ~ 500 nm at room temperature in CHCl3 and revealed that the π-acceptor ability of the phosphorous atom in the ancillary dppmp ligand plays an important role in tuning emission color resulting in a blue-shift emission. The single crystal structure of [(dfmppy)2 Ir(P^N)]PF6 was determined using X-ray crystallography. The iridium metal center adopts a distorted octahedral structure coordinated to two dfmppy and one dppmp ligand, showing cis C-C and trans N-N chelate dispositions. There is a π-π overlap between π electrons delocalized in the difluorophenyl rings.

Novel SNPs in the bovine Transmembrane protein 18 gene, their linkage and their associations with growth traits in Nanyang cattle

Wei Ma,Yun Ma,Dong Liu,Yuan Gao,Xiao-mei Sun,Ai-min Li,Chun-lei Zhang,Hong Chen 한국유전학회 2012 Genes & Genomics Vol.34 No.6

Transmembrane protein 18 (TMEM18) gene is expressed in the central nervous system that has recently been linked to human obesity and body mass index (BMI) in genome wide association studies (GWAS). In this study, two novel single nucleotide polymorphisms (SNPs), g.3835 G > A (aa. Gly >Ser) and g.3865 A > G were detected in cattle TMEM18 gene by DNA sequencing. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and forced PCR-RFLP methods were used to genotype the two SNPs in 1218 Chinese native cattle individuals. The association between novel SNPs and growth traits (especially on body weight and body height) in Nanyang cattle showed that individuals with GG genotype was higher than those with AA genotype at g.3835G>A locus (P < 0.05) in Nanyang cattle. Significant association also revealed that individuals of AA genotype at g. 3865 A>G locus were higher in terms of body weight, average daily gain, chest circunmference, body length (P < 0.05), body height and hucklebone width (P < 0.01) than GG genotypes in Nanyang cattle. Moreover, the effect of XspI-MluI combinations with growth traits in Nanyang cattle revealed that AAGG type had higher body weight, body length, chest circumference and average daily gain (P < 0.05)than GGAG in Nanyang cattle aged at 6 months.

지속성 외래 복막투석 환자에서 혈청 알부민 농도에 영향을 미치는 인자

마경애(Kyoung Ai Ma),강신욱(Shin Wook Kang),최규헌(Kyu Hun Choi),이호영(Ho Yung Lee),한대석(Dae Suk Han),조은영(Eun Young Cho),이종호(Jong Ho Lee),이승우(Seoung Woo Lee) 대한내과학회 1998 대한내과학회지 Vol.54 No.2

Objectives: Protein-calorie malnutrition is a common problem in patients undergoing continuous ambulatory peritoneal dialysis (CAPD), Serum albumin(SA) concentration has been used as a marker for assessing nutritional status. Hypoalbuminemia has been linked to an increased risk of morbidity and mortality and more numerous, prolonged hospitalization for peritoneal dialysis patients. The aim of this study was to determine factors affecting SA value in CAPD patients. Methods: We performed a cross-sectional study which included patients` demographics, anthropometric data, biochemical parameters, urea kinetic data and comorbidity in 106 stable CAPD patients. Results: 1) There were 50 men and 56 women with a mean CAPD duration of 43 months and mean age of 49 years. The mean concentration of SA was 3.9±0.5 (range 2.5-5.3) g/dl and weekly Kt/Vurea 2.0±0.4 (range 1.32-3.79) 2) Twenty-one patients(20%) were classified as group I(SA<3.5g/dl)and the remaining patients(80%) as group II(SA≥3.5g/dl) 3) Group I patients were significantly older(55±11 vs 47±11 years, p<0.05%) and had significantly higher comorbidity score(1.5±0.8 vs 0.7±0.9, p<0.05), C-reactive protein (4.5±0.9 vs 0.5±0.1 mg/dl, p<0.05%), 24-hr dialysate-to-plasma creatinine(D/PCr) ratio(0.84±0.1 vs 0.76±0.1, p<0.05), 24-hr dialysate protein (7167±2031 vs 5471±1515 mg, p<0.05) and had significantly lower residual renal function(RRF)(0.2±03 vs 0.7±1.2 ml/min, p<0.05), BUN(48±14.8 vs 55.6±14.9 mg/dl, p<0.05), serum creatinine(10.4±2.8 vs 12.6±3.5 mg/dl, p<0.05), IGF-1(186±99 vs 260±131 ng/ml, p<0.05), serum phosphorus(4.1±1.2 vs 5.0±1.3 mg /dl, p<0.05) than group II. 4) SA showed positive correlation with anion gap (r=0.43, p value=0.001), transferrin(r-0.41, p value=0.001) phosphorus(r=0.31, p value=0.001) and negative correlation with 24-hr dialysate protein loss(r=-0.51, p value=0.001), 24-hr D/PCr ratio(r=-0.49, p value=0.001), comorbidity score(r=-0.36, p vluue=0.001). NPCB(r=0.22, p vaiue=0.023), IGF-1(r=0.30, p value=0.002), BUN(r=0.23, p ualue=0.016) weakly correlated with SA. 5) By stepwise multiple logistic regression analysis, age, CRP, 24-hr D/PCr ratio and RBF independently influenced SA level. Conclusion: SA level seems to be affected by non-nutritional factors such as age, peritoneal membrane transport characteristics, residual renal function and presence of acute phase protein response manifested by CRP elevation, in addition to nutritional factors.

Wegener`s granulomatosis 환자에서 발생한 cyclophosphamide 에 의한 폐독성 1 예

마경애(Kyoung Ai Ma),최영일(Young Il Choi),엄철(Cheol Eom),이진호(Jin Ho Lee),최영인(Young In Choi),한명호(Myong Ho Han),박경주(Kyung Ju Park),임현이(Hyun Ee Yim),신규태(Gyu Tae Shin),김흥수(Heung Soo Kim),김도헌(Do Hun Kim) 대한내과학회 2001 대한내과학회지 Vol.61 No.4

Lung toxicity associated with cyclophosphamide use is a rare but serious side effect, that may result in a fatal course. However no such cases have been reported in Korea, so clinicians would not be alert to this adverse effect. We recently experienced a woman with Wegener's granulomatosis and idiopathic pulmonary fibrosis. This patient had been administered 12 grams of cyclophosphamide for 4 months. At that time of admission, She felt aggravating dyspnea on exertion for 2 weeks. Her chest X-ray and high resolution CT revealed aggravated reticular opacities and ground glass appearances. Dyspnea was improved and ground glass appearances on HRCT was disappeared after discontinuation of cyclophosphamide. We diagnosed this case as cyclophosphamide-induced pneumonitis and report it with a brief review of the liter ature. (Korean J Med 61:439-443, 2001)

Identification of flutter derivatives of bridge decks using stochastic search technique

Ai-Rong Chen,Fu-You Xu,Ru-Jin Ma 한국풍공학회 2006 Wind and Structures, An International Journal (WAS Vol.9 No.6

A more applicable optimization model for extracting flutter derivatives of bridge decks is presented, which is suitable for time-varying weights for fitting errors and different lengths of vertical bending and torsional free vibration data. A stochastic search technique for searching the optimal solution of optimization problem is developed, which is more convenient in understanding and programming than the alternate iteration technique, and testified to be a valid and efficient method using two numerical examples. On the basis of the section model test of Sutong Bridge deck, the flutter derivatives are extracted by the stochastic search technique, and compared with the identification results using the modified least-square method. The Empirical Mode Decomposition method is employed to eliminate noise, trends and zero excursion of the collected free vibration data of vertical bending and torsional motion, by which the identification precision of flutter derivatives is improved.

Identification of flutter derivatives of bridge decks using stochastic search technique

Chen, Ai-Rong,Xu, Fu-You,Ma, Ru-Jin Techno-Press 2006 Wind and Structures, An International Journal (WAS Vol.9 No.6

A more applicable optimization model for extracting flutter derivatives of bridge decks is presented, which is suitable for time-varying weights for fitting errors and different lengths of vertical bending and torsional free vibration data. A stochastic search technique for searching the optimal solution of optimization problem is developed, which is more convenient in understanding and programming than the alternate iteration technique, and testified to be a valid and efficient method using two numerical examples. On the basis of the section model test of Sutong Bridge deck, the flutter derivatives are extracted by the stochastic search technique, and compared with the identification results using the modified least-square method. The Empirical Mode Decomposition method is employed to eliminate noise, trends and zero excursion of the collected free vibration data of vertical bending and torsional motion, by which the identification precision of flutter derivatives is improved.

The Microbial Mechanisms for Intermittent Drainages on Methane Cycle in Rice Field Soil

Ke Ma,Yahai Lu,Ralf Conrad,Chenwei Ai 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

Clinicopathologic Characteristics and Prognostic Factors in Patients with Operable HER-2 Overexpressing Breast Cancer

Liu, Ai-Na,Sun, Ping,Liu, Jian-Nan,Ma, Jin-Bo,Qu, Hua-Jun,Zhu, Hua,Yu, Cai-Yan,Zhang, Liang-Ming Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.4

Objective: To study the relationship between clinical pathologic characteristics, treatment modalities and prognostic factors in HER-2 (Human Epidermal growth factor Receptor-2) overexpressed breast carcinoma. Materials and Methods: Major clinico-pathological factors including therapeutic modalities and survival status of 371 breast cancer patients with HER2 over-expression, teated at Yantai Yuhuangding Hospital from March of 2002 to December of 2010 were retrospectively studied, with special attention focused on survival-related factors. Results: The median age of the total 371 patients in this study was 48 years at time of diagnosis, among which, the leading pathological type was infiltrating ductal carcinoma (92.5%); 62.8% presented with a primary tomor larger than 2 cm in diameter at diagnosis, 51.0% had axillary lymph node (ALN) metastases; ER (Estrogen receptor)/PR (Progesterone receptor) double negative occured in 52.8% of cases, and PCNA (proliferation cell nuclear antigen) (+++) was found in 55.1%. HER-2 overexpressed patients were usually in advanced stage when the diagnosis was made (72.8% at stages IIA~IIIC). The prognosis and survival were assessed in 259 patients with complete follow-up data. 5-year DFS (disease-free survival) and OS (overall survival) rate was 68.0% and 78.0% respectively. Univariate analysis revealed that age, tumor size, ALN metastases, LVSI (lymph-vascular space involvement), PCNA status, hormonal therapy, chemotherapy cycles, and HER-2 overexpression, correlated closely with the prognosis. ALN metastases, LVSI, PCNA status and chemotherapy cycles were independent predictors of survival. Conclusions: HER-2 overexpressed breast cancer has special clinical and pathological characteristics, with advanced clinical stages and high rate of ER/PR double negative. Lymph node metastases, LVSI, PCNA and chemotherapy cycles are independent predictors of prognosis.