9 research outputs found
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 C<sub>5</sub> and C<sub>6</sub> 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<sup>+</sup>) 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<sup>+</sup> 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<sup>+</sup> ion-exchanged
zeolites on the surface of high porosity, hydrophilic cellulose nanofiber
mats, we can achieve a tunable release of Ag<sup>+</sup> 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 H<sub>2</sub>. 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
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