Coupling organosolv fractionation and reductive depolymerization of woody biomass in a two-step catalytic process

\u3cp\u3eA two-step catalytic process for woody biomass fractionation and valorization is presented. Both lignin and carbohydrate are converted to useful chemicals. Oak sawdust is effectively delignified in methanol using different homogeneous acids (sulphuric acid, aluminium triflate, p-methylbenzenesulfonic acid, hydrochloride acid and phosphoric acid) in the first step, resulting in a lignin oil and cellulose pulp. In the second step, the lignin oil is upgraded to phenolic monomers in methanol in a H\u3csub\u3e2\u3c/sub\u3e atmosphere by a Pd/C catalyst. The degree of delignification correlates inversely with the aromatic monomer yield. Characterization of the lignin oil by gel permeation chromatography and heteronuclear single quantum coherence NMR revealed that the cleavage of β-O-4 bonds during acidolysis is accompanied by repolymerization of lignin fragments. A model compound study shows that species containing unsaturated aldehyde groups are prone to form high molecular-weight products due to repolymerization. The use of Pd/C in combination with H\u3csub\u3e2\u3c/sub\u3eSO\u3csub\u3e4\u3c/sub\u3e or aluminium triflate did not lead to noticeable leaching, whereas severe leaching and Pd particle size growth occurred when HCl and p-TsOH were used as acid catalysts. H\u3csub\u3e3\u3c/sub\u3ePO\u3csub\u3e4\u3c/sub\u3e is the suitable acid catalyst for the present process since the lignin repolymerization is minimized in the first step (160 °C, 2 h, atmospheric N\u3csub\u3e2\u3c/sub\u3e pressure). Up to 25.0 wt% yield of mainly 4-n-propyl syringol/guaiacol and their derivatives was obtained over the Pd/C catalyst in the second step (180 °C, 2 h, 30 bar H\u3csub\u3e2\u3c/sub\u3e). The Pd/C catalyst can be recycled with no significant loss of activity and selectivity after four runs. The cellulose pulp can be easily separated from the other products and shows enhanced susceptibility to enzymatic hydrolysis, resulting in glucose yields as a high as 66 wt%.\u3c/p\u3

Surveillance of HIV infection among injecting drug users in the Netherlands: results Den Haag 2000

Between March 21 and July 3 2000, a serum sample and a questionnaire on risk behaviour were obtained from 217 IDU in Den Haag. Participation was on a voluntary basis. Participants were recruited at methadone treatment sites (35%) and low-threshold daytime care projects (65%). Of 211 IDU, four persons were found to be infected with HIV (prevalence 1.9%, 95% confidence interval [CI] 0.5 - 4.8). Thirtyfive percent of the participants had antibodies to HBc (previous or current HBV-infection), for 3% of the participants HBsAg was detected in the blood (carrier). Of the IDU, 47% had antibodies to HCV. The prevalence of anti-HBc and -HCV is lower than in other cities in the Netherlands. Sixteen (20%) out of 81 currently injecting IDU borrowed syringes or needles in the last 6 months, this level is somewhat higher than in other cities studied in the Netherlands. Twenty percent lent syringes or needles to other IDU. Condom use was very low during sexual contact between steady partners (84% not always using a condom). 48% of the IDU have a non-drug user as a steady sexual partner. With casual partners and clients, condoms were used more often. The risk of further spread of HIV among IDU in Den Haag is low. At this low level of HIV prevalence, the risk of spread to non-IDU or the general population is also low.Tussen 21 maart en 3 juli 2000 werd bij 217 IDs uit Den Haag een bloedmonster en een vragenlijst naar risicogedrag afgenomen. De IDs werden geworven via methadonposten (35%) en laagdrempelige instellingen voor druggebruikers (65%). Van de 211 IDs waren vier deelnemers HIV-positief (prevalentie 1,9%; 95% betrouwbaarheidsinterval [BI] 0,5 - 4,8%). Vijfendertig procent van de deelnemers had antistoffen tegen HBc (vroeger doorgemaakte of huidige HBV-infectie), bij 3% van de deelnemers werd HBsAg aangetoond in het bloed (dragerschap). Bij 47% werden antistoffen aangetoond tegen HCV. De prevalentie van anti-HBc en anti-HCV is lager dan in andere Nederlandse steden. Van de 81 actuele spuiters had 20% in de laatste 6 maanden een gebruikte spuit of naald van een ander geleend, relatief veel in vergelijking met metingen in andere steden. Eveneens 20% had een spuit of naald uitgeleend. Eenenzestig procent van de IDs had in de laatste zes maanden een vaste seksuele partner gehad. Bij 48% van deze IDs was de vaste partner geen druggebruiker, bij 17% een niet-injecterende druggebruiker. Met de vaste seksuele partner werd in 84% van de contacten niet altijd een condoom gebruikt. Met losse partners en met klanten werden condooms vaker gebruikt. Door de lage HIV-prevalentie wordt het risico op verspreiding van HIV naar niet-IDs of de rest van de algemene bevolking laag ingeschat

Surveillance of HIV infection among injecting drug users in the Netherlands: results Den Haag 2000

Tussen 21 maart en 3 juli 2000 werd bij 217 IDs uit Den Haag een bloedmonster en een vragenlijst naar risicogedrag afgenomen. De IDs werden geworven via methadonposten (35%) en laagdrempelige instellingen voor druggebruikers (65%). Van de 211 IDs waren vier deelnemers HIV-positief (prevalentie 1,9%; 95% betrouwbaarheidsinterval [BI] 0,5 - 4,8%). Vijfendertig procent van de deelnemers had antistoffen tegen HBc (vroeger doorgemaakte of huidige HBV-infectie), bij 3% van de deelnemers werd HBsAg aangetoond in het bloed (dragerschap). Bij 47% werden antistoffen aangetoond tegen HCV. De prevalentie van anti-HBc en anti-HCV is lager dan in andere Nederlandse steden. Van de 81 actuele spuiters had 20% in de laatste 6 maanden een gebruikte spuit of naald van een ander geleend, relatief veel in vergelijking met metingen in andere steden. Eveneens 20% had een spuit of naald uitgeleend. Eenenzestig procent van de IDs had in de laatste zes maanden een vaste seksuele partner gehad. Bij 48% van deze IDs was de vaste partner geen druggebruiker, bij 17% een niet-injecterende druggebruiker. Met de vaste seksuele partner werd in 84% van de contacten niet altijd een condoom gebruikt. Met losse partners en met klanten werden condooms vaker gebruikt. Door de lage HIV-prevalentie wordt het risico op verspreiding van HIV naar niet-IDs of de rest van de algemene bevolking laag ingeschat.Between March 21 and July 3 2000, a serum sample and a questionnaire on risk behaviour were obtained from 217 IDU in Den Haag. Participation was on a voluntary basis. Participants were recruited at methadone treatment sites (35%) and low-threshold daytime care projects (65%). Of 211 IDU, four persons were found to be infected with HIV (prevalence 1.9%, 95% confidence interval [CI] 0.5 - 4.8). Thirtyfive percent of the participants had antibodies to HBc (previous or current HBV-infection), for 3% of the participants HBsAg was detected in the blood (carrier). Of the IDU, 47% had antibodies to HCV. The prevalence of anti-HBc and -HCV is lower than in other cities in the Netherlands. Sixteen (20%) out of 81 currently injecting IDU borrowed syringes or needles in the last 6 months, this level is somewhat higher than in other cities studied in the Netherlands. Twenty percent lent syringes or needles to other IDU. Condom use was very low during sexual contact between steady partners (84% not always using a condom). 48% of the IDU have a non-drug user as a steady sexual partner. With casual partners and clients, condoms were used more often. The risk of further spread of HIV among IDU in Den Haag is low. At this low level of HIV prevalence, the risk of spread to non-IDU or the general population is also low.IG

Selective production of mono-aromatics from lignocellulose over Pd/C catalyst:The influence of acid co-catalysts

The ‘lignin-first’ approach has recently gained attention as an alternative whole biomass pretreatment technology with improved yield and selectivity of aromatics compared with traditional upgrading processes using technical lignins. Metal triflates are effective co-catalysts that considerably speed up the removal of lignin fragments from the whole biomass. As their cost is too high in a scaled-up process, we explored here the use of HCl, H2SO4, H3PO4 and CH3COOH as alternative acid co-catalysts for the tandem reductive fractionation process. HCl and H2SO4 were found to show superior catalytic performance over H3PO4 and CH3COOH in model compound studies that simulate lignin-carbohydrate linkages (phenyl glycoside, glyceryl trioleate) and lignin intralinkages (guaiacylglycerol-β-guaiacyl ether). HCl is a promising alternative to the metal triflate as co-catalyst in the reductive fraction of woody biomass. Al(OTf)3 and HCl respectively afforded 46 wt% and 44 wt% lignin monomers from oak wood sawdust in a tandem catalytic systems with Pd/C at 180 ⁰C in 2 h. The retention of cellulose in the solid residue was nearly similar.\u3cbr/\u3e\u3cbr/\u3

Deactivation of Sn-Beta during carbohydrate conversion

\u3cp\u3eThe deactivation of Sn-Beta zeolite catalyst during retro-aldolization and isomerization of glucose is investigated. Confocal fluorescence microscopy reveals that retro-aldolization of glucose in CH\u3csub\u3e3\u3c/sub\u3eOH at 160 °C is accompanied with the build-up of insoluble oligomeric deposits in the micropores, resulting in a rapid catalyst deactivation. These deposits accumulate predominantly in the outer regions of the zeolite crystals, which points to mass transport limitations. Glucose isomerization in water is not only accompanied by the formation of insoluble deposits in the micropores, but also by the structural degradation of the zeolite due to desilication and destannation. Enhanced and sustained catalytic performance can be achieved by using ethanol/water mixtures as the reaction solvent instead of water.\u3c/p\u3

A clinical practice guideline for physiotherapists treating patients with chronic obstructive pulmonary disease based on a systematic review of available evidence

PURPOSE: Update of a clinical practice guideline for the physiotherapy management of patients with chronic obstructive pulmonary disease supporting the clinical decision-making process. METHODS: A systematic computerized literature search was performed on different modalities for improving physical exercise capacity, reducing exertional dyspnoea, improving airway clearance and encouraging changes in physical activity behaviour. Methodological quality was scored with the PEDro Scale. Scientific conclusions were graded according to the criteria of the; Dutch Evidence Based Guideline Development Platform'. These, together with practical considerations, were used to formulate recommendations for clinical practice. RESULTS: A total of 103 studies were included in the systematic review, consisting of five meta-analyses of randomized controlled trials, 84 randomized controlled trials and 14 uncontrolled studies. Twenty scientific conclusions supported six recommendations on physical exercise training. Nineteen scientific conclusions supported eight recommendations on interventions for reducing dyspnoea. Five scientific conclusions supported seven recommendations concerning treatment modalities to improve mucus clearance, and two scientific conclusions supported two recommendations on strategies for encouraging permanent changes in physical activity behaviour. CONCLUSIONS: Strong recommendations support the use of physical exercise training to improve health-related quality of life and functional exercise capacity. Future research should investigate whether additional interventions for reducing exertional dyspnoea have a place as adjuncts to physical exercise training in selected patients. In addition, treatment of impaired mucus clearance, especially during acute exacerbations, requires further research. With the advance of new technologies for objective measurements of physical activities in daily life more research is needed concerning interventions to initiate and maintain physical activity behaviour change during and after supervised physical exercise training programmes