Origins of the short circuit current of a current mismatched multijunction photovoltaic cell considering subcell reverse breakdown.

In the photovoltaic community, short circuit current (Isc) of a current mismatched multijunction photovoltaic (MJPV) cell was usually thought to be limited by the lowest subcell photocurrent (Imin). However, under certain conditions for multijunction solar cells, Isc≠Imin was observed by researchers, while this effect has not been studied in multijunction laser power converters (MJLPCs). In this work, we provide an in-depth analysis of the formation mechanisms for the Isc of the MJPV cell by measuring I-V curves of the GaAs and InGaAs LPCs with different number of subcells and simulating the I-V curves with the reverse breakdown of each subcell considered. It is found that Isc of an N-junction PV cell can be theoretically equal to any current value within a range from a current lower than Imin to the maximum subcell photocurrent, which is up to the number of subcell current steps in the forward biased I-V curve. An MJPV cell with a constant Imin will demonstrate a higher Isc if it has more subcells, smaller subcell reverse breakdown voltage and smaller series resistance. As a result, Isc tends to be limited by the photocurrent of a subcell closer to the middle cell and is less sensitive to the optical wavelength than Imin. This should be another possible reason why the measured EQE of a multijunction LPC exhibits a wider spectrum width than the calculated Imin-based EQE, whereas this was usually attributed to the luminescent coupling effect merely.

The role of the maximal first derivative of the radial pulse wave (Rad dP/dtmax) in monitoring cardiac function.

BACKGROUND: This study aimed to assess the clinical significance of the maximal first derivative of the radial pulse wave (Rad dP/dtmax) in monitoring cardiac function with different perioperative patients by researching the relationship between Rad dP/dtmax and cardiac output (CO). METHODS: Patients with non-pump coronary artery bypass grafting (CABG) and open liver tumor resection (OLTR) were enrolled in this study (n=10). CO was measured using the thermodilution Swan-Ganz catheter method and Rad dP/dtmax was acquired by the analysis of patients' left radial artery pressure waveform through the PowerLab data acquisition device. CO, Rad dP/dtmax, heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure, central venous pressure, mean pulmonary arterial pressure, pulmonary artery wedge pressure (PAW), and body surface area was recorded. Data were analyzed using a mixed linear model of time-dependent covariates to duplicate the data. RESULTS: The bivariate correlation coefficients of Rad dP/dtmax and CO were 0.526 and 0.413. The result of the multivariate mixed linear model analysis showed that compared with other indicators, Rad dP/dtmax had the greatest standardized coefficient with CO in CABG patients. While in OLTR patients, HR, SBP, PAW, and DBP had larger standardized coefficients. CONCLUSIONS: Rad dP/dtmax could be a useful indicator to reflect and predict the acute changes in cardiac function in perioperative patients, especially for patients with cardiac dysfunction or contractility abnormality.

[Preparation of Coated CMC-Fe0 Using Rheological Phase Reaction Method and Research on Degradation of TCE in Water].

The coated nanoscale zero-valent iron (coated CMC-Fe0) was synthesized with cheap and environment friendly CMC as the coating agent using rheological phase reaction. The sample was characterized by means of XRD, SEM, TEM and N2 adsorption-stripping and used to study reductive dechlorination of TCE. The experimental results indicated that the removal rate of TCE was about 100% when the CMC-Fe0 dosage was 6 g x L(-1), the initial TCE concentration was 5 mg x L(-1) and the reaction time was 40 h. The TCE degradation reaction of coated CMC-Fe0 followed a pseudo-first-order kinetic model. Finally, the product could be simply recovered.

Expression of CCL2 and CCR2 in the hippocampus and the interventional roles of propofol in rat cerebral ischemia/reperfusion.

The aim of the present study was to determine the roles of the chemotactic factor, chemokine ligand 2 (CCL2), and its receptor, chemokine receptor type 2 (CCR2), in the hippocampus of rats with cerebral ischemia/reperfusion injury. In total, 24 Sprague-Dawley rats, weighting 250-300 g, were randomly divided into three groups (n=8): Sham-operated (C group), cerebral ischemia/reperfusion injury (I/R group) and propofol-intervention (P group) groups. The rats were sacrificed at 6 h after the ischemia/reperfusion surgery, and the brains were obtained to isolate the hippocampus. The mRNA expression levels of CCL2 and CCR2 in the hippocampus were analyzed by quantitative polymerase chain reaction, while the protein expression levels of CCL2 and CCR2 were determined by western blot analysis. The expression levels of CCL2 and CCR2 in the procerebrum were markedly elevated in the I/R and P groups at 6 h after the ischemia/reperfusion surgery when compared with the C group (P<0.05). In addition, the mRNA expression levels of CCL2 and CCR2 decreased significantly in the P group as compared with that in the I/R group (P<0.05). Therefore, CCL2 and CCR2 may be involved in the mechanisms underlying cerebral ischemia/reperfusion injury, and propofol may protect the brain through regulating the expression of CCL2 and CCR2.

The predictive and therapeutic value of thymidine phosphorylase and dihydropyrimidine dehydrogenase in capecitabine (Xeloda)-based chemotherapy for head and neck cancer.

OBJECTIVES: To evaluate whether two molecular biomarkers, thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD), could be clinically useful in predicting and improving the chemotherapeutic outcome of the oral fluoropyrimidine capecitabine (5'-DFUR or Xeloda), in the treatment of human head and neck squamous cell carcinoma (HNSCC). EXPERIMENTAL DESIGN: Quantitative reverse-transcriptase polymerase chain reaction was used to determine the TP and DPD expression levels in different HNSCC cell lines. The TP to DPD ratio was calculated and compared to the relative chemosensitivity between cell lines after treatment with 5'-DFUR. The effect of TP transgene expression to alter the TP to DPD ratio and hence optimize the therapeutic outcome of capecitabine treatment was further evaluated in a murine model of human HNSCC using immunohistochemistry to detect TP and DPD expression in vivo. RESULTS: No correlation was detected between sensitivity to 5'-DFUR and the relative expression levels of TP or DPD in the multiple HNSCC cell lines tested. However, significant correlation was observed between the TP to DPD ratio versus drug resistance of the HNSCC cells (r = -0.914, p = 0.0281). In addition, we demonstrate that transgene expression of TP significantly enhanced the tumoricidal effect of capecitabine in HNSCC tumors with otherwise low endogenous TP to DPD ratios. This antitumor effect was observed up to 30 days after treatment. CONCLUSIONS: The results of this study suggest that HNSCC patients who would most benefit from capecitabine-based chemotherapy could be identified by examining the TP to DPD ratio of their tumors. Furthermore, we demonstrate the potential role of TP gene therapy in TP to DPD ratio manipulation to optimize the tumoricidal effect of capecitabine.

Combination nonviral interleukin 2 gene therapy and external-beam radiation therapy for head and neck cancer.

OBJECTIVES: To demonstrate that the combination of nonviral murine interleukin 2 (mIL-2) gene therapy and external-beam radiation therapy (XRT) have an enhanced therapeutic effect for the treatment of head and neck squamous cell carcinoma (HNSCC) in an orthotopic murine model and to elucidate the mechanism of action. METHODS: Randomized, controlled studies in the murine orthotopic model of HNSCC. Squamous cell carcinoma VII cells were injected into the floor of the mouth to establish tumors in immunocompetent mice. The intervention groups were treated with mIL-2, radiation therapy, empty plasmid, no treatment, combination mIL-2/XRT, and combination empty plasmid/XRT. Nonviral mIL-2 gene transfer was performed on days 5 and 9. The XRT was administered to the assigned groups 24 hours after first mIL-2 delivery. The mice were killed on day 13. Tumors and local lymph nodes were harvested and evaluated. Primary and secondary cytokine expression, cytotoxic T-lymphocyte activity, and apoptosis were assayed. RESULTS: The combination mIL-2/XRT demonstrated a significant increase in antitumor effects compared with single therapy or controls. Increased expression levels of primary and secondary cytokines were found in the group treated with mIL-2, and this effect was preserved when mIL-2 treatment was combined with XRT. Combination therapy significantly increased apoptosis compared with monotherapy. CONCLUSIONS: The present study demonstrates that combination mIL-2/XRT generates potent antitumor immune responses and significantly increases apoptosis in an orthotopic murine model of HNSCC. Further optimization of this strategy is warranted as well as consideration for human clinical trials.