Synthesis of Hierarchical Sn-MFI as Lewis Acid Catalysts for Isomerization of Cellulosic Sugars

Hierarchical stannosilicate molecular sieves with ordered mesoporosity and MFI topology (three dimensionally ordered mesoporous imprinted (3DOm-i) Sn-MFI) were successfully synthesized within the confined space of three dimensionally ordered mesoporous (3DOm) carbon by a seeded growth method. The obtained 3DOm-i Sn-MFI consisting of 30 nm spherical elements forming an opaline structure contains highly ordered mesopores ranging from 4 to 11 nm. Compared with conventional Sn-MFI, 3DOm-i Sn-MFI exhibits superior catalytic performance for the isomerization of cellulosic sugars. No diffusion limitation was observed for the isomerization of a triose sugar, dihydroxyacetone (DHA), into methyl lactate (ML). The presence of weak Brønsted acid in the 3DOm-i Sn-MFI catalyst facilitates the reaction by catalyzing the formation of an intermediate, pyruvaldehyde (PA). 3DOm-i Sn-MFI offers significant improvements for the isomerizations of C₅ and C₆ sugars, such as xylose and glucose, by greatly enhancing molecular transport. The reaction rate of xylose on 3DOm-i Sn-MFI is at least 20 times higher than that on conventional bulky sized Sn-MFI. The reaction rate for glucose is also enhanced by using 3DOm-i Sn-MFI, but to a lesser extent as compared with the reaction of xylose, possibly because glucose cannot diffuse into the 10-membered-ring pore of MFI, and the reaction is catalyzed only on the external surface of the Sn-MFI catalysts. Moreover, the combination of seeded growth with confined synthesis allows us to synthesize hierarchical Sn-MFI using commercially available carbon materials, such as carbon black and activated carbon, indicating that the synthesis strategy is a versatile and reliable method for tailoring the structure of hierarchical zeolites

Antimicrobial Activity of Silver Ions Released from Zeolites Immobilized on Cellulose Nanofiber Mats

In this study, we exploit the high silver ion exchange capability of Linde Type A (LTA) zeolites and present, for the first time, electrospun nanofiber mats decorated with in-house synthesized silver (Ag⁺) ion exchanged zeolites that function as molecular delivery vehicles. LTA-Large zeolites with a particle size of 6.0 μm were grown on the surface of the cellulose nanofiber mats, whereas LTA-Small zeolites (0.2 μm) and three-dimensionally ordered mesoporous-imprinted (LTA-Meso) zeolites (0.5 μm) were attached to the surface of the cellulose nanofiber mats postsynthesis. After the three zeolite/nanofiber mat assemblies were ion-exchanged with Ag⁺ ions, their ion release profiles and ability to inactivate Escherichia coli (E. coli) K12 were evaluated as a function of time. LTA-Large zeolites immobilized on the nanofiber mats displayed more than an 11 times greater E. coli K12 inactivation than the Ag-LTA-Large zeolites that were not immobilized on the nanofiber mats. This study demonstrates that by decorating nanometer to micrometer scale Ag⁺ ion-exchanged zeolites on the surface of high porosity, hydrophilic cellulose nanofiber mats, we can achieve a tunable release of Ag⁺ ions that inactivate bacteria faster and are more practical to use in applications over powder zeolites

Anal Human Papillomavirus Infection among HIV-Infected Men in Korea

<div><p>Background</p><p>Little is known about the epidemiology on human papillomavirus (HPV) infection among HIV-infected men in Korea. The objective of this study was to determine the prevalence, genotype distribution and risk factors associated with anal HPV infection among HIV-infected men in Korea.</p><p>Methods</p><p>A single-center cross-sectional study was conducted with HIV-infected men in Korea. Participants completed a detailed sexual behavior risk factor questionnaire. Anal samples were collected for cytology and HPV genotyping. Factors associated with anal HPV infection were assessed using multivariable logistic regression, stratifying by sexual behaviour.</p><p>Results</p><p>A total of 201 HIV-infected men were included in the study: 133 were from men who have sex with men (MSM) and 68 from men who have sex with women (MSW). Any anal HPV infection was detected in 82.7% of HIV-infected MSM and in 51.5% of HIV- infected MSW (<i>P</i> < 0.001). High-risk HPV (HR-HPV) prevalence was higher among MSM (47.4%) than MSW (25.0%; <i>P</i> = 0.002). The HR-HPV types identified most frequently were HPV 16 (11%), HPV 18 (9.9%), and HPV 58 (5%) in MSM, and HPV 58(11%) and HPV 16 (8.9%) in MSW. Prevalence of any HPV types in 9-valent vaccine types was higher among MSM than MSW (47.4% vs 22.1%. <i>P</i> = 0.001). Abnormal anal cytology was more commonly detected in MSM than MSW (42.9% vs.19.1%, <i>P</i> < 0.001). In HIV-infected MSM, higher number of lifetime male sex partners was significantly associated with any anal HPV infection, but age was a significant risk factor associated with anal HR-HPV infection.</p><p>Conclusion</p><p>Anal HPV infection was highly prevalent in HIV-infected MSM in Korea, and also commonly found in HIV-infected MSW. In HIV-infected MSM, the significant risk factor for being infected with any HPV infection was lifetime number of male sexual partners, and with anal oncogenic HPV infection was age.</p></div

Renewable Isoprene by Sequential Hydrogenation of Itaconic Acid and Dehydra-Decyclization of 3‑Methyl-Tetrahydrofuran

Catalytic hydrogenation of itaconic acid (obtained from glucose fermentation) yields 3-methyl-tetrahydrofuran (3-MTHF), which then undergoes catalytic dehydra-decyclization to isoprene. It is demonstrated that a one-pot cascade reaction converts itaconic acid to 3-MTHF at ∼80% yield with Pd–Re/C catalyst and 1000 psig H₂. Subsequent gas-phase catalytic ring opening and dehydration of 3-MTHF with phosphorus-containing zeolites including P-BEA, P-MFI, and P-SPP (self-pillared pentasil) exhibits 90% selectivity to dienes (70% isoprene, 20% pentadienes) at 20–25% conversion

Baseline characteristics.

<p>Baseline characteristics.</p

Univariable and multivariable analyses of determinants of anal human papillomavirus infection in HIV-infected Men who have sex with men.

<p>Univariable and multivariable analyses of determinants of anal human papillomavirus infection in HIV-infected Men who have sex with men.</p

Univariable and multivariable analyses of determinants of high risk human papillomavirus infection in HIV-infected Men who have sex with men.

<p>Univariable and multivariable analyses of determinants of high risk human papillomavirus infection in HIV-infected Men who have sex with men.</p

Prevalence of Human papillomavirus (HPV) infection and abnormal anal cytology.

<p>Prevalence of Human papillomavirus (HPV) infection and abnormal anal cytology.</p

Human papillomavirus (HPV) genotypic distribution among HIV-infected Men who have sex with men and among HIV-infected men who have sex with women.

<p>(MSM, men who have sex with men; MSW, men who have sex with women; U, untypeable)</p