Is soil quality improvement by legume cover crops a function of the initial soil chemical characteristics?

The aim of this study, which was conducted in a humid savannah zone of central Côte d’Ivoire, was to examine changes in the quality of soil cultivated with herbaceous legume cover crops as a function of initial soil characteristics. Mucuna pruriens var utilis and Pueraria phaseoloides were used in a two side-by-side location experiment: a shrubby savannah (the savannah site or “SAV”) and a natural fallow dominated by Chromolaena odorata (the fallow site or “FAL”). The latter was mainly characterized by higher organic matter [organic carbon (C) 10 vs. 7.5 mg kg^?1; total nitrogen (N) 0.8 vs. 0.5 mg kg^?1) and total phosphorus (P) (282.3 vs. 168.3 mg kg^?1) contents in the upper soil layer (0–10 cm). After 8 months of growth, biomass production by M. pruriens was found to be 6.5 and 4.9 t dry matter (DM) ha^?1 at FAL and SAV, respectively. For P. phaseoloides, the values were 7.2 and 6.4 t DM ha^?1, respectively, in approximately the same period. The quantities of nutrients released by decomposing legume litter were higher at FAL than at SAV. Between-site differences in soil quality improvement were most noticeable in terms of available P, microbial biomass carbon (MBC) and MBC:total carbon (TC) ratio. The FAL site experienced a faster improvement of soil parameters under both legume species: available P increased from 18 to 58 mg kg^?1 under M. pruriens, and from 19 to 52 mg kg^?1 under P. phaseoloides; MBC increased from 88 to 185 mg kg^?1 under M. pruriens, and from 127 to 192 mg kg^?1 under P. phaseoloides. In contrast, the parameters remained constant over time at SAV. Soil C and N contents as well as C mineralization showed similar trends at both sites. Based on these results, we conclude that soil quality improvement under cover crops appears to be faster when the initial soil organic C, total N and P contents are adequate. These findings will be useful in assisting governmental decision-making on approaches to be taken for restoring soil fertility in low-input agricultural systems in West Africa.     

Effects of silicone coating degradation on GaN MQW LEDs performances using physical and chemical analyses

This work presents a physics of failure (POF) methodology coupling failure signatures with physico-chemical analyses. The aim is to work out electro-optical failure signatures located in packaged InGaN/GaN Multiple Quantum Wells Light Emitting Diodes (MQW LEDs). Electrical and optical characteristics performed after accelerated ageing tests (30 mA/85 °C/1500 h), confirm a 65% drop of optical power and an increase of one decade of leakage current spreading at the silicone oil/chip interfaces. Through measurements of silicone coating fluorescence emission spectra, we demonstrate that the polymer enlarges the LED emission spectrum and shifts central wavelength. This shift is related to silicone oil spectral instability and the central wavelength of packaged LED appears to be temperature insensitive. In this paper, we discriminate the degradation of bulk silicone oil responsible for optical losses from the polymer/chip interface inducing larger leakage current.     

Lithium bis(fluorosulfonyl)imide (LiFSI) as conducting salt for nonaqueous liquid electrolytes for lithium-ion batteries: Physicochemical and electrochemical properties

Lithium bis(fluorosulfonyl)imide (LiFSI) has been studied as conducting salt for lithium-ion batteries, in terms of the physicochemical and electrochemical properties of the neat LiFSI salt and its nonaqueous liquid electrolytes. Our pure LiFSI salt shows a melting point at 145 °C, and is thermally stable up to 200 °C. It exhibits far superior stability towards hydrolysis than LiPF₆. Among the various lithium salts studied at the concentration of 1.0 M (= mol dm⁻³) in a mixture of ethylene carbonate (EC)/ethyl methyl carbonate (EMC) (3:7, v/v), LiFSI shows the highest conductivity in the order of LiFSI > LiPF₆ > Li[N(SO₂CF₃)₂] (LiTFSI) > LiClO₄ > LiBF₄. The stability of Al in the high potential region (3.0-5.0 V vs. Li⁺/Li) has been confirmed for high purity LiFSI-based electrolytes using cyclic voltammetry, SEM morphology, and chronoamperometry, whereas Al corrosion indeed occurs in the LiFSI-based electrolytes tainted with trace amounts of LiCl (50 ppm). With high purity, LiFSI outperforms LiPF₆ in both Li/LiCoO₂ and graphite/LiCoO₂ cells.     

Chloride free Pt‐ and PtRu‐ Nanoparticles Stabilised by “Armand's Ligand” as Precursors for Fuel Cell Catalysts

Chloride residues on the surface of fuel cell catalysts are known to decrease the catalytic activity, especially for O₂ reduction. Using Armand's ligand, which contains the chloride free DCTA anion, for the colloidal stabilisation of nanoscopic Pt and PtRu catalysts precursors (< 2 nm size) leads to PEMFC and DMFC catalysts with improved activity compared to commercial E‐TEK catalysts as evidenced by both methanol oxidation and CO‐stripping voltametric studies.     

Desorption isotherms,net isosteric heat and the effect of temperature and water activity on the antioxidant activity of two varieties of onion (Allium cepa L)

The standard static gravimetric method was used to determine moisture desorption isotherms (MDIs) of two onion varieties (Goudami and Galmi Violet) at 30 °C, 45 °C and 60 °C in the water activity ranging from 0.055 to 0.83. The combined effects of temperature and water activity on the antioxidant activities of the onion varieties were also studied. GAB, Oswin, Smith and BET equations were tested to fit the experimental data. The net isosteric heat of sorption was calculated. Equilibrium moisture content (EMC), total phenolic content (TPC) and antiradical activity were also measured. The isotherm and the EMC vary significantly with the onion variety and drying temperature, irrespective of water activity (a_w). Desorption isotherms were best described by the GAB model. The maximum net isosteric heats for Galmi Violet (32.58 kJ mol^?1) were greater than those of Goudami (23.50 kJ mol^?1) at each EMC. The TPC and antiradical activity of the Galmi Violet were significantly (P ≤ 0.05) higher than that of the Goudami at all investigated temperatures and water activities.     

Final report of a phase II study of chemotherapy with bleomycin, epirubicin, and cisplatin for locally advanced and metastatic/recurrent undifferentiated carcinoma of the nasopharyngeal type

PURPOSE: This article presents an assessment of the combination of bleomycin, epirubicin, and cisplatin as induction chemotherapy before radiotherapy in the treatment of undifferentiated carcinoma of the nasopharyngeal type in patients with recurrent/metastatic disease (group A), and in previously untreated patients with locoregionally advanced disease (UICC-AJCC 87, N2-3, M0) (group B) in terms of toxicity, antitumoral activity, and therapeutic efficacy. PATIENTS AND METHODS: From January 1987 to September 1990, 111 consecutive patients with histologically proven UCNT were treated with six cycles of intravenous cisplatin (100 mg/m2 day 1) epirubicin (80 mg/m2 day 1), and bleomycin (15 mg bolus day 1), followed by 16 mg/m2/day continuous infusion for 5 days, repeated every 21 days for three cycles. Three further cycles without bleomycin were given to 44 patients in group A. In group B (67 patients), only three cycles of the same protocol were given, with a slightly lower dose of epirubicin (70 mg/m2), followed by conventional radiotherapy (70 Gy/7 weeks). RESULTS: Of 44 patients entered in group A, 38 were evaluable for response. We observed 9 (20%) complete responses and 11 (25%) partial responses, for a 45% overall response rate. In 12 patients not previously given chemotherapy, there were 4 complete responses, compared to 5 complete responses in 32 patients previously treated with chemotherapy. Four patients are alive with no evidence of disease after 53+, 60+, 61+, and 72+ months. In group B the overall response rate to chemotherapy was 98% with 42 complete (62%) and 24 partial responses (36%). Three months after the end of radiotherapy, the overall complete response rate was 94% (63 patients). After a median follow-up time of 77 months (range, 53-94), the 4-year overall survival and disease-free survival rates for this group are 66% and 60%, respectively. The median disease-free survival has not been reached at 90 months. CONCLUSION: The results of the BEC combination trial are very encouraging in metastatic and recurrrent UCNT, with durable remissions in this poor-prognosis population. The results in patients with locally advanced disease have motivated prospective phase III testing of the neoadjuvant chemotherapy approach to evaluate its impact on locoregionally advanced disease (> or =N2MO UICC-AJCC 87).     

Sequence-specific polypeptoids: a diverse family of heteropolymers with stable secondary structure

We have synthesized and characterized a family of structured oligo-N-substituted-glycines (peptoids) up to 36 residues in length by using an efficient solid-phase protocol to incorporate chemically diverse side chains in a sequence-specific fashion. We investigated polypeptoids containing side chains with a chiral center adjacent to the main chain nitrogen. Some of these sequences have stable secondary structure, despite the achirality of the polymer backbone and its lack of hydrogen bond donors. In both aqueous and organic solvents, peptoid oligomers as short as five residues give rise to CD spectra that strongly resemble those of peptide alpha-helices. Differential scanning calorimetry and CD measurements show that polypeptoid secondary structure is highly stable and that unfolding is reversible and cooperative. Thermodynamic parameters obtained for unfolding are similar to those obtained for the alpha-helix to coil transitions of peptides. This class of biomimetic polymers may enable the design of self-assembling macromolecules with novel structures and functions.