Heat Transfer Enhancement Technique of PCMs and Its Lattice Boltzmann Modeling

Phase change materials (PCMs) have several advantages for thermal energy storage due to their high energy storage density and nearly constant working temperature. Unfortunately, the low thermal conductivity of PCM impedes its efficiency of charging and discharging processes. To solve this issue, different techniques are developed to enhance the heat transfer capability of PCMs. In this chapter, the common approaches, which include the use of extended internal fins, porous matrices or metal foams, high thermal conductivity nanoparticles, and heat pipes for enhancing the heat transfer rate of PCMs, are presented in details. In addition, mathematical modeling plays a significant role in clarifying the PCM melting and solidification mechanisms and directs the experiments. As a powerful mesoscopic numerical approach, the enthalpy-based lattice Boltzmann method (LBM), which is robust to investigate the solid-liquid phase change phenomenon without iteration of source terms, is also introduced in this chapter, and its applications in latent heat thermal energy storage (LHTES) unit using different heat transfer enhancement techniques are discussed

The fundamental mechanism of single-phase convective heat transfer enhancement : the field synergy princple and its applications

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.In this keynote lecture a comprehensive review is presented for the field synergy principle (FSP) which was proposed at the 11th International Heat Transfer Conference in 1998 and later further enhanced by many researchers, including the present authors. The lecture is organized as follows. A brief introduction to the FSP is presented in section 1. In Section 2, discussion is given to the indications of the synergy degree between velocity and temperature gradient. In Section 3, numerous examples are provided to show the validity of the principle. In Section 4 a special experimental verification of the principle is provided. In Section 5 numerical examples are provided to demonstrate that the field synergy principle can unify all the existing explanations of single-phase convective heat transfer enhancement. Section 6 is devoted to the applications of the field synergy principle in developing new types of enhanced surfaces for heat transfer. Finally some conclusions are drawn.cs201

Critical role of ASCT2-mediated amino acid metabolism in promoting leukaemia development and progression

Amino acid (AA) metabolism is involved in diverse cellular functions, including cell survival and growth, however it remains unclear how it regulates normal hematopoiesis versus leukemogenesis. Here, we report that knockout of Slc1a5 (ASCT2), a transporter of neutral AAs, especially glutamine, results in mild to moderate defects in bone marrow and mature blood cell development under steady state conditions. In contrast, constitutive or induced deletion of Slc1a5 decreases leukemia initiation and maintenance driven by the oncogene MLL-AF9 or Pten deficiency. Survival of leukemic mice is prolonged following Slc1a5 deletion, and pharmacological inhibition of ASCT2 also decreases leukemia development and progression in xenograft models of human acute myeloid leukemia. Mechanistically, loss of ASCT2 generates a global effect on cellular metabolism, disrupts leucine influx and mTOR signaling, and induces apoptosis in leukemic cells. Given the substantial difference in reliance on ASCT2-mediated AA metabolism between normal and malignant blood cells, this in vivo study suggests ASCT2 as a promising therapeutic target for the treatment of leukemia

The State of Grasslands across Inner Mongolia and Mongolia

Grasslands across Inner Mongolia and Mongolia, with their long history of nomadic livestock grazing, are very important natural resources for animal husbandry and environmental services. The main types of grasslands are meadow steppe (forest steppe), typical steppe (steppe) and desert steppe. Most of the grasslands are degraded due to over-grazing, which reduces animal production and the values of environmental services. Overgrazing decreases plant production, species biodiversity, ecosystem stability, soil fertility & structure, and lowers animal productivity leading to reduced household incomes. In pastoral areas across Inner Mongolia and Mongolia, degraded grasslands can be rehabilitated by better managing stocking rates. Our surveys, experiments and farm demonstrations have found that, in degraded grasslands, lower stocking rates had benefits for animal production, net incomes and environmental services. To implement these improvements across Inner Mongolia and Mongolia will be challenging to avoid deleterious trade-offs with livelihoods as it will require changes in herder practices. Further research and demonstration are required to develop locally relevant systems

Clinicopathological Significance and Prognostic Value of DNA Methyltransferase 1, 3a, and 3b Expressions in Sporadic Epithelial Ovarian Cancer

Altered DNA methylation of tumor suppressor gene promoters plays a role in human carcinogenesis and DNA methyltransferases (DNMTs) are responsible for it. This study aimed to determine aberrant expression of DNMT1, DNMT3a, and DNMT3b in benign and malignant ovarian tumor tissues for their association with clinicopathological significance and prognostic value. A total of 142 ovarian cancers and 44 benign ovarian tumors were recruited for immunohistochemical analysis of their expression. The data showed that expression of DNMT1, DNMT3a, and DNMT3b was observed in 76 (53.5%), 92 (64.8%) and 79 (55.6%) of 142 cases of ovarian cancer tissues, respectively. Of the serious tumors, DNMT3a protein expression was significantly higher than that in benign tumor samples (P = 0.001); DNMT3b was marginally significant down regulated in ovarian cancers compared to that of the benign tumors (P = 0.054); DNMT1 expression has no statistical difference between ovarian cancers and benign tumor tissues (P = 0.837). Of the mucious tumors, the expression of DNMT3a, DNMT3b, and DNMT1 was not different between malignant and benign tumors. Moreover, DNMT1 expression was associated with DNMT3b expression (P = 0.020, r = 0.195). DNMT1 expression was associated with age of the patients, menopause status, and tumor localization, while DNMT3a expression was associated with histological types and serum CA125 levels and DNMT3b expression was associated with lymph node metastasis. In addition, patients with DNMT1 or DNMT3b expression had a trend of better survival than those with negative expression. Co-expression of DNMT1 and DNMT3b was significantly associated with better overall survival (P = 0.014). The data from this study provided the first evidence for differential expression of DNMTs proteins in ovarian cancer tissues and their associations with clinicopathological and survival data in sporadic ovarian cancer patients