The challenge of high temperatures in deep mining remains harmful to the health of workers and their production efficiency The addition of phase change materials (PCMs) to filling slurry and the use of the cold storag...The challenge of high temperatures in deep mining remains harmful to the health of workers and their production efficiency The addition of phase change materials (PCMs) to filling slurry and the use of the cold storage function of these materials to reduce downhole temperatures is an effective approach to alleviate the aforementioned problem.Paraffin–CaCl_(2)·6H_(2)O composite PCM was prepared in the laboratory.The composition,phase change latent heat,thermal conductivity,and cemented tailing backfill (CTB) compressive strength of the new material were studied.The heat transfer characteristics and endothermic effect of the PCM were simulated using Fluent software.The results showed the following:(1) The new paraffin–CaCl_(2)·6H_(2)O composite PCM improved the thermal conductivity of native paraffin while avoiding the water solubility of CaCl_(2)·6H_(2)O.(2) The calculation formula of the thermal conductivity of CaCl_(2)·6H_(2)O combined with paraffin was deduced,and the reasons were explained in principle.(3) The“enthalpy–mass scale model”was applied to calculate the phase change latent heat of nonreactive composite PCMs.(4)The addition of the paraffin–CaCl_(2)·6H_(2)O composite PCM reduced the CTB strength but increased its heat absorption capacity.This research can give a theoretical foundation for the use of heat storage backfill in green mines.展开更多
O6-methylguanine-DNA methyltransferase (MGMT) plays an important role in repairing alkylated DNA. MGMT activity as well as cellular sensitivity to 1- ( 4- amino- 2-methyl-5-pyrimidinyl) methyl-3- ( 2-chloroethyl)-3-ni...O6-methylguanine-DNA methyltransferase (MGMT) plays an important role in repairing alkylated DNA. MGMT activity as well as cellular sensitivity to 1- ( 4- amino- 2-methyl-5-pyrimidinyl) methyl-3- ( 2-chloroethyl)-3-nitrosourea (ACNU) of 20 Chinese tumor cell strains were assayed. A linear response between MGMT activity and ACNU sensitivity (D10) was observed. The lower the MGMT activity In the cells, the more the sensitivity to ACNU killing. It suggested that assay of MGMT activity in tumor biopsy could be used as a guide to predict the effectiveness of ACNU treatment in chemotherapy of human cancer.展开更多
The tumor selectivity of alkylating agents that produce guanine O6-chloroethyl (laromustine and carmustine) and O6-methyl (temozolomide) lesions depends upon O6-methylguanine-DNA methyltransferase (MGMT) activity bein...The tumor selectivity of alkylating agents that produce guanine O6-chloroethyl (laromustine and carmustine) and O6-methyl (temozolomide) lesions depends upon O6-methylguanine-DNA methyltransferase (MGMT) activity being lower in tumor than in host tissue. Despite the established role of MGMT as a tumor resistance factor, consensus on how to assess MGMT expression in clinical samples is unsettled. The aim of this study is to examine the relationship between the values derived from distinctive MGMT measurements in 13, 12, 6 and 2 pairs of human tumors and matched normal adjacent tissue from the colon, kidney, lung and liver, respectively, and in human cell lines. The MGMT measurements included 1) alkyl-transfer assays using [benzene-3H]O6-benzylguanine as a substrate to assess functional MGMT activity, 2) methylation-specific PCR (MSP) to probe MGMT gene promoter CpG methylations as a measure of gene silencing, and 3) western immunoblots to analyze the MGMT protein. In human cell lines, a strict negative correlation existed between MGMT activity and the extent of promoter methylation. In tissue specimens, by contrast, the correlation between these two variables was low. Moreover, alkyl-transfer assays identified 3 pairs of tumors and normal tissue with tumor-selective reduction in MGMT activity in the absence of promoter methylation. Cell line MGMT migrated as a single band in western analyses, whereas tissue MGMT was heterogeneous around its molecular size and at much higher molecular masses, indicative of multi-layered post-translational modifications. Malignancy is occasionally associated with a mobility shift in MGMT. Contrary to the prevalent expectation that MGMT expression is governed at the level of gene silencing, these data suggest that other mechanisms that can lead to tumorselective reduction in MGMT activity exist in human tissue.展开更多
O6-Methylguanine-DNA methyltransferase （MGMT） is a cellular DNA repair protein that rapidly reverses alkylation （e.g. methylation） at the O6 position of guanine, thereby neutralizing the cytotoxic effects of alkyl...O6-Methylguanine-DNA methyltransferase （MGMT） is a cellular DNA repair protein that rapidly reverses alkylation （e.g. methylation） at the O6 position of guanine, thereby neutralizing the cytotoxic effects of alkylating agent therapy such as temozolomide （TMZ） and carmustine. It has been shown that epigenetic silencing of the MGMT gene by promoter methylation shuts down gene transcription and reflects a common alteration in primary human tumors leading to MGMT deficiency. Epigenetic silencing of the MGMT gene has been shown to correlate with improved survival in several studies of glioma patients treated with the alkylating agent therapy and has been substantiated in two clinical trials.展开更多
Driven by the demands of diverse artificial intelligence(AI)-enabled application,Mobile Edge Computing(MEC)is considered one of the key technologies for 6G edge intelligence.In this paper,we consider a serial task mod...Driven by the demands of diverse artificial intelligence(AI)-enabled application,Mobile Edge Computing(MEC)is considered one of the key technologies for 6G edge intelligence.In this paper,we consider a serial task model and design a quality of service(QoS)-aware task offloading via communication-computation resource coordination for multi-user MEC systems,which can mitigate the I/O interference brought by resource reuse among virtual machines.Then we construct the system utility measuring QoS based on application latency and user devices’energy consumption.We also propose a heuristic offloading algorithm to maximize the system utility function with the constraints of task priority and I/O interference.Simulation results demonstrate the proposed algorithm’s significant advantages in terms of task completion time,terminal energy consumption and system resource utilization.展开更多
基金financial support provided by the National Natural Science Foundation of China (No. 52174106)the Key Technology Research and Development Program (No. 2022YFC2905102)。
文摘The challenge of high temperatures in deep mining remains harmful to the health of workers and their production efficiency The addition of phase change materials (PCMs) to filling slurry and the use of the cold storage function of these materials to reduce downhole temperatures is an effective approach to alleviate the aforementioned problem.Paraffin–CaCl_(2)·6H_(2)O composite PCM was prepared in the laboratory.The composition,phase change latent heat,thermal conductivity,and cemented tailing backfill (CTB) compressive strength of the new material were studied.The heat transfer characteristics and endothermic effect of the PCM were simulated using Fluent software.The results showed the following:(1) The new paraffin–CaCl_(2)·6H_(2)O composite PCM improved the thermal conductivity of native paraffin while avoiding the water solubility of CaCl_(2)·6H_(2)O.(2) The calculation formula of the thermal conductivity of CaCl_(2)·6H_(2)O combined with paraffin was deduced,and the reasons were explained in principle.(3) The“enthalpy–mass scale model”was applied to calculate the phase change latent heat of nonreactive composite PCMs.(4)The addition of the paraffin–CaCl_(2)·6H_(2)O composite PCM reduced the CTB strength but increased its heat absorption capacity.This research can give a theoretical foundation for the use of heat storage backfill in green mines.
文摘O6-methylguanine-DNA methyltransferase (MGMT) plays an important role in repairing alkylated DNA. MGMT activity as well as cellular sensitivity to 1- ( 4- amino- 2-methyl-5-pyrimidinyl) methyl-3- ( 2-chloroethyl)-3-nitrosourea (ACNU) of 20 Chinese tumor cell strains were assayed. A linear response between MGMT activity and ACNU sensitivity (D10) was observed. The lower the MGMT activity In the cells, the more the sensitivity to ACNU killing. It suggested that assay of MGMT activity in tumor biopsy could be used as a guide to predict the effectiveness of ACNU treatment in chemotherapy of human cancer.
文摘The tumor selectivity of alkylating agents that produce guanine O6-chloroethyl (laromustine and carmustine) and O6-methyl (temozolomide) lesions depends upon O6-methylguanine-DNA methyltransferase (MGMT) activity being lower in tumor than in host tissue. Despite the established role of MGMT as a tumor resistance factor, consensus on how to assess MGMT expression in clinical samples is unsettled. The aim of this study is to examine the relationship between the values derived from distinctive MGMT measurements in 13, 12, 6 and 2 pairs of human tumors and matched normal adjacent tissue from the colon, kidney, lung and liver, respectively, and in human cell lines. The MGMT measurements included 1) alkyl-transfer assays using [benzene-3H]O6-benzylguanine as a substrate to assess functional MGMT activity, 2) methylation-specific PCR (MSP) to probe MGMT gene promoter CpG methylations as a measure of gene silencing, and 3) western immunoblots to analyze the MGMT protein. In human cell lines, a strict negative correlation existed between MGMT activity and the extent of promoter methylation. In tissue specimens, by contrast, the correlation between these two variables was low. Moreover, alkyl-transfer assays identified 3 pairs of tumors and normal tissue with tumor-selective reduction in MGMT activity in the absence of promoter methylation. Cell line MGMT migrated as a single band in western analyses, whereas tissue MGMT was heterogeneous around its molecular size and at much higher molecular masses, indicative of multi-layered post-translational modifications. Malignancy is occasionally associated with a mobility shift in MGMT. Contrary to the prevalent expectation that MGMT expression is governed at the level of gene silencing, these data suggest that other mechanisms that can lead to tumorselective reduction in MGMT activity exist in human tissue.
文摘O6-Methylguanine-DNA methyltransferase （MGMT） is a cellular DNA repair protein that rapidly reverses alkylation （e.g. methylation） at the O6 position of guanine, thereby neutralizing the cytotoxic effects of alkylating agent therapy such as temozolomide （TMZ） and carmustine. It has been shown that epigenetic silencing of the MGMT gene by promoter methylation shuts down gene transcription and reflects a common alteration in primary human tumors leading to MGMT deficiency. Epigenetic silencing of the MGMT gene has been shown to correlate with improved survival in several studies of glioma patients treated with the alkylating agent therapy and has been substantiated in two clinical trials.
基金funded in part by the Open Research Fund of the Shaanxi Province Key Laboratory of Information Communication Network and Security under Grant No.ICNS202003in part supported by BUPT Excellent Ph.D.Students Foundation under Grant CX2022210。
文摘Driven by the demands of diverse artificial intelligence(AI)-enabled application,Mobile Edge Computing(MEC)is considered one of the key technologies for 6G edge intelligence.In this paper,we consider a serial task model and design a quality of service(QoS)-aware task offloading via communication-computation resource coordination for multi-user MEC systems,which can mitigate the I/O interference brought by resource reuse among virtual machines.Then we construct the system utility measuring QoS based on application latency and user devices’energy consumption.We also propose a heuristic offloading algorithm to maximize the system utility function with the constraints of task priority and I/O interference.Simulation results demonstrate the proposed algorithm’s significant advantages in terms of task completion time,terminal energy consumption and system resource utilization.
