Chemicals from lignin: an interplay of lignocellulose fractionation, depolymerisation, and upgrading.

In pursuit of more sustainable and competitive biorefineries, the effective valorisation of lignin is key. An alluring opportunity is the exploitation of lignin as a resource for chemicals. Three technological biorefinery aspects will determine the realisation of a successful lignin-to-chemicals valorisation chain, namely (i) lignocellulose fractionation, (ii) lignin depolymerisation, and (iii) upgrading towards targeted chemicals. This review provides a summary and perspective of the extensive research that has been devoted to each of these three interconnected biorefinery aspects, ranging from industrially well-established techniques to the latest cutting edge innovations. To navigate the reader through the overwhelming collection of literature on each topic, distinct strategies/topics were delineated and summarised in comprehensive overview figures. Upon closer inspection, conceptual principles arise that rationalise the success of certain methodologies, and more importantly, can guide future research to further expand the portfolio of promising technologies. When targeting chemicals, a key objective during the fractionation and depolymerisation stage is to minimise lignin condensation (i.e. formation of resistive carbon-carbon linkages). During fractionation, this can be achieved by either (i) preserving the (native) lignin structure or (ii) by tolerating depolymerisation of the lignin polymer but preventing condensation through chemical quenching or physical removal of reactive intermediates. The latter strategy is also commonly applied in the lignin depolymerisation stage, while an alternative approach is to augment the relative rate of depolymerisation vs. condensation by enhancing the reactivity of the lignin structure towards depolymerisation. Finally, because depolymerised lignins often consist of a complex mixture of various compounds, upgrading of the raw product mixture through convergent transformations embodies a promising approach to decrease the complexity. This particular upgrading approach is termed funneling, and includes both chemocatalytic and biological strategies.

Relationships of isometric mid-thigh pull variables to weightlifting performance.

AIM: The purpose of this study was to evaluate the relationship between weightlifting performance (snatch, clean and jerk, and total) and variables obtained from the isometric mid-thigh pull (IMTP). METHODS: Twelve weightlifters, ranging from novice to advanced, performed the IMTP 10 days after a competition. Correlations were used to evaluate relationships between variables of the IMTP and absolute and scaled competition results. RESULTS: Unscaled competition results correlated strongly with IRFD (0-200ms: r=0.567-0.645, 0-250ms: r=0.722-0.781) while results correlated weakly with Peak IRFD (5ms window, r=0.360-0.426). Absolute peak force values correlated very strongly with absolute values for the competition performance (r=0.830-0.838). Force at 100ms, 150ms, 200ms and 250ms also correlated strongly with competition results (r=0.643-0.647, r=0.605-0.636, r=0.714-0.732, r=0.801-0.804). Similar findings were noted for allometrically scaled values. CONCLUSION: Measures of average IRFD probably represent a more relevant variable to dynamic performance than does Peak IRFD (5ms). Maximum isometric strength also is likely to have a strong role in weightlifting performance.

Recovery of cardiac function after standard hypothermic storage versus preservation with Peg-hemoglobin.

Preservation of the heart for transplantation after infusion of cardioplegia and extirpation of a cardiac allograft results in an ischemic insult to the myocardium. This ischemic insult may lead to a loss of function in the transplanted heart. Hypothermic perfusion preservation with an oxygen hemoglobin carrying solution may avert ischemic injury and lead to improved recovery of cardiac function. The purpose of this study was to compare cardiac function after 8 hours of continuous hypothermic perfusion with a unique polyethylene-glycol-hemoglobin (PEG-Hb) solution to hearts preserved by 4 hours of hypothermic ischemic storage. Freshly extirpated hearts served as functional controls. The hearts of 26 anesthetized and intubated New Zealand white rabbits were harvested after cold cardioplegic arrest. Group I (n = 12) hearts were perfused with a PEG-Hb solution at 20 degrees C and 30 mm Hg for 8 hours. PO2 was maintained > or = 500 mm Hg. Group II (n = 7) hearts were preserved by cold ischemic storage for 4 hours at 4 degrees C. Group III (n = 7) were tested immediately after harvest. Left ventricular (LV) function was measured in the nonworking state at 15 minutes, 1 hour, and 2 hours after transfer to a standard crystalloid Langendorff circuit. Measurement of LV developed pressure, peak + dP/dt and -dP/dt revealed a superior trend between Group I and Group II hearts in comparison with freshly extirpated hearts. Heart rate was similar among all groups throughout testing (p = ns). Coronary blood flow was not significantly different between groups. Continuous perfusion preservation of rabbit hearts for 8 hours with PEG-Hb solution at 30 mm Hg and 20 degrees C yielded LV function that was similar to 4 hours of ischemic hypothermic storage. Furthermore, return of cardiac function after 8 hours of perfusion preservation using this PEG-Hb solution may be superior to that obtained in freshly extirpated hearts. These data suggest that some recovery of myocardial function may occur during perfusion preservation with this PEG-Hb solution after the ischemic insult of cardioplegic arrest. Continuous perfusion preservation using this PEG-Hb solution deserves further investigation in large animal transplant models.

Ex vivo cardiac allograft preservation by continuous perfusion techniques.

The current technique of cardiac preservation for clinical transplantation by infusion of cold cardioplegia and immersion of the heart in an isotonic saline bath at 4 degrees C limits safe tissue preservation time to 4 to 6 hours. The myriad of benefits to be gained by extending cardiac preservation time has prompted the search for alternatives to hypothermic immersion of the heart, the most promising of which involves techniques of coronary artery perfusion. Countless studies have shown the benefits of long-term storage of donor hearts by perfusion rather than the immersion technique. Continuous perfusion preservation has three basic advantages over simple immersion. Perfusion preservation with oxygen carrying solutions has the advantage of preventing ischemia, anaerobic metabolism, and reperfusion injury. Second, nutritional supplementation and provision of substrate can be more effectively delivered to myocardial cells. Third, continuous perfusion preservation effects the clearance of metabolic waste products from the coronary circulation. The composition of the ideal perfusion solution and optimal preservation conditions remain incompletely defined.

Exfoliative dermatitis.

Exfoliative dermatitis, also known as erythroderma, is an uncommon but serious skin disorder that family physicians must be able to recognize and treat appropriately. Although the etiology is often unknown, exfoliative dermatitis may be the result of a drug reaction or an underlying malignancy. The approach to treatment should include discontinuation of any potentially causative medications and a search for any underlying malignancy. One of the most common malignancies associated with exfoliative dermatitis is cutaneous T-cell lymphoma, which may not manifest for months or even years after the onset of the skin condition. Hospitalization is usually necessary for initial evaluation and treatment. In the hospital, special attention must be given to maintaining temperature control, replacing lost fluids and electrolytes, and preventing and treating infection. The long-term prognosis is good in patients with drug-induced disease, although the course tends to be remitting and relapsing in idiopathic cases. The prognosis of cases associated with malignancy typically depends on the outcome of the underlying malignancy.