A new two-dimensional magic-angle spinning NMR experiment 1,2 using multiple-quantum coherences of half-integer quadrupolar nuclei was used to study 27 Al sites in crystalline samples of leucite (KAlSi 2 O 6 ), anorthite (CaAl 2 Si 2 O 8 ), and kyanite (Al 2 SiO 5 ), as well as CaAl 2 Si 2 O 8 glass and a magnesium aluminoborate glass. In the crystals, multiple sites are partially resolved and new results for isotropic chemical shifts and quadrupolar parameters are derived, using data collected at a single magnetic field. Data for both leucite and anorthite are consistent with previous results that correlate chemical shifts with mean intertetrahedral bond angle. Signal can be obtained from sites with quadrupolar coupling constants as large as 9 MHz, but intensities are reduced. In the aluminoborate glass, peaks for sites with different Al coordination numbers are well separated. The lack of such features in CaAl 2 Si 2 O 8 glass rules out the presence of significant quantities of AlO 5 and AlO 6 groups.

BackgroundAnastomotic leakage is a serious complication associated with anterior resection for rectal cancer, the long-term effects of which are unclear. Therefore, a systematic review and meta-analysis were conducted to evaluate the impact of anastomotic leakage on disease recurrence and survival.MethodsWe searched PubMed, Embase, and the Cochrane Library databases from their inception to January 2016. Studies evaluating the oncologic impact of anastomotic leakage were included in the meta-analysis. Outcome measures were local recurrence, overall survival, cancer-specific survival, and distant recurrence. Pooled hazard ratio (HR) with 95 % confidence interval (CI) was calculated using random effects models.ResultsFourteen studies containing 11,353 patients met inclusion criteria. Anastomotic leakage was associated with a greater local recurrence (HR 1.71; 95 % CI 1.22–2.38) and decreased in both overall survival (HR 1.67; 95 % CI 1.19–2.35) and cancer-specific survival (HR 1.30; 95 % CI 1.08–1.56); anastomotic leakage did not increase distant recurrence (HR 1.03; 95 % CI 0.76–1.40).ConclusionsAnastomotic leakage was associated with high local recurrence and poor survival (both overall and cancer-specific), but not with distant recurrence.

Multiple-quantum magic-angle spinning (MQMAS) 17 O NMR spectroscopy has been applied to study boron oxide, sodium borate, sodium potassium borosilicate, and sodium boroaluminate glasses. Up to eight distinct oxygen sites are identified, with the chemical shift and quadrupolar coupling parameters determined for each. Previous assignment of the B-O-B and Si-O-B resonances has been found to be incorrect. In contrast to standard models of glass structure, three-coordinated boron mixes with the silicon oxide network to a great extent. Sodium borosilicate glasses with low-sodium content are likely to be phase-separated on the nanoscale. Those with intermediate sodium content form homogeneous glasses with boron atoms distributed evenly in the SiO 2 network. A boron avoidance rule analogous to the aluminum avoidance rule may apply in this region, when BO 4 groups are abundant. Adding excess sodium cations to the system may again lead to compositional heterogeneity. The existence of diborate group as the basic building unit in glasses with appropriate sodium content is not well supported. The network-forming cations in sodium boroaluminate glasses are well mixed, with no Al-O-Al resonance observed by MQMAS. The effect of cation type and thermal history on glass structures is also discussed.