Effects of Nanopowder Additives in Micro-electrical Discharge Machining

Tan, Peng-Cheong,Yeo, Swee-Hock,Tan, Yie-Voon Korean Society for Precision Engineering 2008 International Journal of Precision Engineering and Vol.9 No.3

The use of electrical discharge machining (EDM) for micro-machining applications requires particular attention to the machined surface roughness and discharge gap distance, as these factors affect the geometrical accuracy of micro-parts. Previous studies of conventional EDM have shown that selected types of semi-conductive and non-conductive powder suspended in the dielectric reduced the surface roughness while ensuring a limited increase in the gap distance. Based on this, an extension of the technique to micro-EDM was studied Such work is necessary since the introduction of nanopowders suspended in the dielectric is not well understood. The experimental results showed that a statistically significant reduction in the surface roughness value was achieved at particular concentrations of the powder additives, depending on the powder material and the machining input energy setting. The average reduction in surface roughness using a powder suspended dielectric was between 14-24% of the average surface roughness generated using a pure dielectric. Furthermore, when these additive concentrations were used for machining, no adverse increase in the gap distance was observed.

Effects of Nanopowder Additives in Micro-electrical Discharge Machining

Peng-Cheong Tan,Swee-Hock Yeo,Yie-Voon Tan 한국정밀공학회 2008 International Journal of Precision Engineering and Vol.9 No.3

The use of electrical discharge machining(EDM) for micro-machining applications requires particular attention to the machined surface roughness and discharge gap distance, as these factors affect the geometrical accuracy of micro-parts. Previous studies of conventional EDM have shown that selected types of semi-conductive and nonconductive powder suspended in the dielectric reduced the surface roughness while ensuring a limited increase in the gap distance. Based on this, an extension of the technique to micro-EDM was studied. Such work is necessary since the introduction of nanopowders suspended in the dielectric is not well understood The experimental results showed that a statistically significant reduction in the surface roughness value was achieved at particular concentrations of the powder additives, depending on the powder material and the machining input energy setting. The average reduction in surface roughness using a powder suspended dielectric was between 14-24% of the average surface roughness generated using a pure dielectric. Furthermore, when these additive concentrations were used for machining, no adverse increase in the gap distance was observed.

Comparative Evaluation of Three Purification Methods for the Nucleocapsid Protein of Newcastle Disease Virus from Escherichia coli Homogenates

Tan Yan Peng,Ling Tau Chuan,Yusoff Khatijah,Tan Wen Siang,Tey Beng Ti The Microbiological Society of Korea 2005 The journal of microbiology Vol.43 No.3

In the present study, the performances of conventional purification methods, packed bed adsorption (PBA), and expanded bed adsorption (EBA) for the purification of the nucleocapsid protein (NP) of Newcastle disease virus (NDV) from Escherichia coli homogenates were evaluated. The conventional methods for the recovery of NP proteins involved multiple steps, such as centrifugation, precipitation, dialysis, and sucrose gradient ultracentrifugation. For the PBA, clarified feedstock was used for column loading, while in EBA, unclarified feedstock was used. Streamline chelating immobilized with $Ni^{2+}$ ion was used as an affinity ligand for both PBA and EBA. The final protein yield obtained in conventional and PBA methods was $1.26\%$ and $5.56\%$, respectively. It was demonstrated that EBA achieved the highest final protein yield of $9.6\%$ with a purification factor of 7. Additionally, the total processing time of the EBA process has been shortened by 8 times compared to that of the conventional method.

Comparative Evaluation of Three Purification Methods for the NucleocapsidProtein of Newcastle Disease Virus from Escherichia coli Homogenates

Yan Peng Tan,Tau Chuan Ling,Khatijah Yusoff,Wen Siang Tan,Beng Ti Tey 한국미생물학회 2005 The journal of microbiology Vol.43 No.3

In the present study, the performances of conventional purification methods, packed bed adsorption (PBA), and expanded bed adsorption (EBA) for the purification of the nucleocapsid protein (NP) of Newcastle disease virus (NDV) from Escherichia coli homogenates were evaluated. The conventional methods for the recovery of NP proteins involved multiple steps, such as centrifugation, precipitation, dialysis, and sucrose gradient ultracentrifugation. For the PBA, clarified feedstock was used for column loading, while in EBA, unclarified feedstock was used. Streamline chelating immobilized with Ni2+ ion was used as an affinity ligand for both PBA and EBA. The final protein yield obtained in conventional and PBA methods was 1.26% and 5.56%, respectively. It was emonstrated that EBA achieved the highest final protein yield of 9.6% with a purification factor of 7. Additionally, the total processing time of the EBA process has been shortened by 8 times compared to that of the conventional method.

Transcriptome Sequencing Reveals the Potential Mechanisms of Modified Electroconvulsive Therapy in Schizophrenia

Wanhong Peng,Qingyu Tan,Minglan Yu,Ping Wang,Tingting Wang,Jixiang Yuan,Dongmei Liu,Dechao Chen,Chaohua Huang,Youguo Tan,Kezhi Liu,Bo Xiang,Xuemei Liang 대한신경정신의학회 2021 PSYCHIATRY INVESTIGATION Vol.18 No.5

Objective Schizophrenia (SCZ) is one of the most common and severe mental disorders. Modified electroconvulsive therapy (MECT) is the most effective therapy for all kinds of SCZ, and the underlying molecular mechanism remains unclear. This study is aim to detect the molecule mechanism by constructing the transcriptome dataset from SCZ patients treated with MECT and health controls (HCs).Methods Transcriptome sequencing was performed on blood samples of 8 SCZ (BECT: before MECT; AECT: after MECT) and 8 HCs, weighted gene co-expression network analysis (WGCNA) was used to cluster the different expression genes, enrichment and protein-protein interaction (PPI) enrichment analysis were used to detect the related pathways.Results Three gene modules (black, blue and turquoise) were significantly associated with MECT, enrichment analysis found that the long-term potentiation pathway was associated with MECT. PPI enrichment p-value of black, blue, turquoise module are 0.00127, <1×10^-16 and 1.09×10^-13, respectively. At the same time, EP300 is a key node in the PPI for genes in black module, which got from the transcriptome sequencing data.Conclusion It is suggested that the long-term potentiation pathways were associated with biological mechanism of MECT.

Carbon capture by alkaline absorbent using octadecyltrichlorosilane modified PVDF/TiO2 membrane

Why-Ling Tan,Hoi-Fang Tan,Nor Aini Ahmad,Norhaziyana Hamzah,Abdul Latif Ahmada,Choe Peng Leo 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.3

Carbon capture efficiency of membrane gas absorption was improved using a nearly superhydrophobic membrane. This membrane, polyvinylidene fluoride (PVDF) membrane, was blended with TiO2 nanoparticles and post-modified with octadecyltrichloro silane to reduce wetting. Wetting reduction is important to minimize mass transfer resistance in membrane pores during carbon capture. The hydrophilic TiO2 nanoparticles reduced membrane pore size and hydrophobicity in dual bath coagulation, but they offered active sites for silane modification as proven by Fourier-transform infrared spectra to achieve a water contact angle up to 148.8o. A non-wetting surface near to Cassie- Baxter state was formed due to the nano-roughness of TiO2 nanoparticles and hydrophobic functional groups of silane. The modified membrane showed higher CO2 absorption flux in comparison to the neat PVDF membrane, as much as 114% improvement. The modified membrane also achieved faster carbon capture into water. Furthermore, PVDF and PVDF/TiO2 membranes modified with octadecyltrichloro silane in ethanol (volume ratio of 5 : 50) were less affected by NaOH absorbent, displaying great potential for carbon capture and storage using alkaline waste.

Real-Time Tumor Gene Expression Profiling to Direct Gastric Cancer Chemotherapy: Proof-of-Concept “3G” Trial

Yong, Wei Peng,Rha, Sun Young,Tan, Iain Bee-Huat,Choo, Su-Pin,Syn, Nicholas L.,Koh, Vivien,Tan, Shi-Hui,Asuncion, Bernadette Reyna,Sundar, Raghav,So, Jimmy Bok-Yan,Shabbir, Asim,Tan, Chee-Seng,Kim, Hy American Association for Cancer Research 2018 Clinical Cancer Research Vol.24 No.21

<P><B>Purpose:</B> The oxaliplatin plus S-1 and cisplatin plus S-1 regimens are interchangeably used in the management of advanced gastric cancer. The previously reported G-intestinal (G1) and G-diffuse (G2) intrinsic gene expression signatures showed promise for stratifying patients according to their tumor sensitivity to oxaliplatin or cisplatin.</P><P><B>Experimental Design:</B> The proof-of-concept, multicenter, open-label phase II “3G” trial was done to prospectively evaluate the feasibility and efficacy of using genomic classifiers to tailor treatment in gastric cancer. Patients’ tumors were classified as “G1” or “G2” using a nearest-prediction template method, or “G3” (unclear assignment) when FDR ≥ 0.05. The first 30 patients in the “G1” cohort were assigned oxaliplatin plus S-1 (SOX) chemotherapy; thereafter, subsequently recruited “G1” patients were treated with cisplatin plus S-1 (SP) chemotherapy. “G2” patients and “G3” patients were treated with SP and SOX chemotherapy, respectively.</P><P><B>Results:</B> A total of 48, 21, and 12 patients, respectively, were given “G1,” “G2,” and “G3” genomic assignments. Median turnaround time was 7 days (IQR, 5–9). Response rates were 44.8%, 8.3%, 26.7%, and 55.6% for the “G1-SOX,” “G1-SP,” “G2,” “G3” cohorts, respectively; and was higher in G1 patients treated with SOX compared with SP (<I>P</I> = 0.033). Exploratory analyses using the genomic classifier of Lei and colleagues validated the utility of the metabolic signature as a biomarker for predicting benefit from chemotherapy (log-rank <I>P</I> = 0.004 for PFS), whereas the Asian Cancer Research Group classifier did not demonstrate any predictive value.</P><P><B>Conclusions:</B> This bench-to-bedside effort establishes a reasonable turnaround time for gene expression profiling and possible utility of genomic classifiers in gastric cancer treatment stratification. <I>Clin Cancer Res; 24(21); 5272–81. ©2018 AACR</I>.</P>

Outcome of minimally-invasive versus open pancreatectomies for solid pseudopapillary neoplasms of the pancreas: A 2:1 matched case-control study

Hwee Leong Tan,Ek Khoon Tan,Jin Yao Teo,Juinn Huar Kam,Ser Yee Lee,Peng Chung Cheow,Prema Raj Jeyaraj,Pierce K. Chow,Alexander Y. Chung,London L. Ooi,Chung Yip Chan,Brian K. P. Goh 한국간담췌외과학회 2019 Annals of hepato-biliary-pancreatic surgery Vol.23 No.3

Backgrounds/Aims: Solid pseudopapillary neoplasm (SPPN) is typically seen in young healthy females who would likely benefit from minimally-invasive pancreatectomy (MIP). A few comparative studies have suggested that MIP is associated with favorable outcomes when compared to the open approach for SPPN. This study aims to mitigate potential selection bias by performing a matched case-control study comparing MIP vs open pancreatectomy (OP) for SPPN. Methods: We performed a single-institution retrospective electronic chart review of all patients who underwent surgery for pathologically confirmed SPPN between 2000 and 2017. A 2:1 matched comparison using age, gender, tumor size and the type of pancreatectomy was performed between OP and MIP. Results: A total of 40 patients with a median age of 40.3 years (range 16.5-64.4) and female sex predominance (n=34, 85.0%) underwent surgery during the study period. Nine patients underwent MIP. Matched comparison between 18 OP and 9 MIP demonstrated that MIP was associated with a longer median operating time (305 vs 180 min, p=0.046) and shorter median postoperative stay (6 vs 9 days, p=0.015). There were no significant differences in intraoperative blood loss, blood transfusion requirements, postoperative morbidity (including postoperative pancreatic fistula) and mortality, resection margins, lymph node yield and long-term survival. Conclusions: MIP is a safe and viable option in the management of SPPN with the benefit of a shorter postoperative length of stay at the expense of a longer operation time. There was no significant difference in oncologic outcomes between both groups of patients.

Outcomes of salvage liver transplant for recurrent hepatocellular carcinoma

Yuxin Guo,Ek-Khoon Tan,Thinesh-Lee Krishnamoorthy,Chee-Kiat Tan,Ban-Hock Tan,Thuan-Tong Tan,Ser-Yee Lee,Chung-Yip Chan,Peng-Chung Cheow,Alexander Y. F. Chung,Prema Raj Jeyaraj,Brian K. P. Goh 한국간담췌외과학회 2019 Annals of hepato-biliary-pancreatic surgery Vol.23 No.1

Backgrounds/Aims: Salvage liver transplantation (SLT) is a therapeutic strategy for recurrent hepatocellular carcinoma (HCC). However, it remains controversial with compromised survival outcomes and increased perioperative morbidity compared to primary liver transplant (PLT). In the present work, we describe our institution’s experience on SLT by comparing outcomes of SLT to PLT for HCCs. Methods: Retrospective analysis was conducted for 49 transplant patients from 2006-2017. A comparative analysis was carried out between 14 SLT patients and 35 PLT patients. Results: SLT patients demonstrated significantly shorter time to recurrence than PLT patients (median=5.5 versus 23 months, p<0.001) with a trend towards increased perioperative major morbidity (42.9% versus 37%, p=0.711), inferior 5-year overall survival (61% versus 75%, p=0.345) and inferior 5-year recurrence-free survival (57% versus 72%, p=0.263). However, overall survival from the point of primary resection over a 10-year period showed no statistical difference between the 2 groups (SLT=60% versus PLT=61%, p=0.685). Conclusions: SLT is a viable treatment strategy for HCCs. However, it exhibited poorer short-term perioperative and oncologic outcomes than PLT. SLT requires better patient selection with liver donor grafts for optimization of resource allocation in this era of organ shortage. Considering the worldwide shortages in liver grafts, it is hypothesized that optimization of a salvage transplant strategy may improve resource allocation and reap optimal patient outcomes.

Human capital, financial constraints, and innovation investment persistence

Peng Hongxing,Tan Hongping,Zhang Yin 기술경영경제학회 2020 ASIAN JOURNAL OF TECHNOLOGY INNOVATION Vol.28 No.3

We examine the impact of human capital on innovation investment persistence using a sample of high-tech companies listed in the Chinese A-share market for the period 2009–2017. We find that human capital mitigates the negative effect of financial constraints on innovation investment persistence. We further explore the mechanism through which human capital at the management and employee levels affects innovation investment persistence. We find that management human capital affects innovation investment persistence through the expectation of authorised patents, while employee human capital affects the persistence through salary stickiness. Furthermore, we find that management human capital contributes to an increase in future granted patents through persistent innovation investment.