Characterization of Micro- and Mesoporous Materials Using Accelerated Dynamics Adsorption

Porosimetry is a fundamental characterization technique used in development of new porous materials for catalysis, membrane separation, and adsorptive gas storage. Conventional methods like nitrogen and argon adsorption at cryogenic temperatures suffer from slow adsorption dynamics especially for microporous materials. In addition, CO₂, the other common probe, is only useful for micropore characterization unless being compressed to exceedingly high pressures to cover all required adsorption pressures. Here, we investigated the effect of adsorption temperature, pressure, and type of probe molecule on the adsorption dynamics. Methyl chloride (MeCl) was used as the probe molecule, and measurements were conducted near room temperature under nonisothermal condition and subatmospheric pressure. A pressure control algorithm was proposed to accelerate adsorption dynamics by manipulating the chemical potential of the gas. Collected adsorption data are transformed into pore size distribution profiles using the Horvath–Kavazoe (HK), Saito–Foley (SF), and modified Kelvin methods revised for MeCl. Our study shows that the proposed algorithm significantly speeds up the rate of data collection without compromising the accuracy of the measurements. On average, the adsorption rates on carbonaceous and aluminosilicate samples were accelerated by at least a factor of 4–5

Genetic Substructure of Kuwaiti Population Reveals Migration History

<div><p>The State of Kuwait is characterized by settlers from Saudi Arabia, Iran, and other regions of the Arabian Peninsula. The settlements and subsequent admixtures have shaped the genetics of Kuwait. High prevalence of recessive disorders and metabolic syndromes (that increase risk of diabetes) is seen in the peninsula. Understanding the genetic structure of its population will aid studies designed to decipher the underlying causes of these disorders. In this study, we analyzed 572,366 SNP markers from 273 Kuwaiti natives genotyped using the illumina HumanOmniExpress BeadChip. Model-based clustering identified three genetic subgroups with different levels of admixture. A high level of concordance (Mantel test, p=0.0001 for 9999 repeats) was observed between the derived genetic clusters and the surname-based ancestries. Use of Human Genome Diversity Project (HGDP) data to understand admixtures in each group reveals the following: the first group (Kuwait P) is largely of West Asian ancestry, representing Persians with European admixture; the second group (Kuwait S) is predominantly of city-dwelling Saudi Arabian tribe ancestry, and the third group (Kuwait B) includes most of the tent-dwelling Bedouin surnames and is characterized by the presence of 17% African ancestry. Identity by Descent and Homozygosity analyses find Kuwait’s population to be heterogeneous (placed between populations that have large amount of ROH and the ones with low ROH) with Kuwait S as highly endogamous, and Kuwait B as diverse. Population differentiation F_ST estimates place Kuwait P near Asian populations, Kuwait S near Negev Bedouin tribes, and Kuwait B near the Mozabite population. F_ST distances between the groups are in the range of 0.005 to 0.008; distances of this magnitude are known to cause false positives in disease association studies. Results of analysis for genetic features such as linkage disequilibrium decay patterns conform to Kuwait’s geographical location at the nexus of Africa, Europe, and Asia.</p> </div

Plot (Phylogenetic tree) of pairwise F_ST distances for the three Kuwaiti groups with a set of representative HGDP populations that cover Europe, Asia, and Middle East.

<p>Bootstrap confidence – Red: 70% to 80%; Blue -80% to 90%; Green -90% to 100%.</p

Ancestry composition of Kuwaiti groups using HGDP data.

<p>STRUCTURE results for the combined data set of three Kuwaiti groups and representative HGDP populations from West Asia (Brahui), Middle East (Bedouin, Druze and Palestinian), Mozabite (North Africa), Europe (French), and sub-Saharan Africa (Yoruba). Best Model for the combined data set is at K = 9. Structure results for the combined data set of three Kuwaiti groups and all of the HGDP populations are given in Figure S1. Red: French_Basque (Europe), Green: Bedouin (Arabs), Dark Green: Kalash (Asia), Cyan: Yoruba (sub-Saharan Africa), Blue: Druze (Persian) and Gray: Brahui as inferred from Figure S1. Black lines partition the groups.</p

Linkage disequilibrium (LD) decay across the genomes of the Kuwaiti groups and other representative populations from the HGDP data set.

<p>Linkage disequilibrium (LD) decay across the genomes of the Kuwaiti groups and other representative populations from the HGDP data set.</p

Ancestry estimates using STRUCTURE program for Kuwaiti samples.

<p>(Best model at K= 3). The three groups comprise 138, 63, and 72 individuals, respectively. For simplicity, we label the groups as Kuwait 1, Kuwait 2 and Kuwait 3 (from left to right). Mantel test correlation between pairs of all 4 separate runs (see Materials and Methods) is >0.99 with p-value = 1e-04 over 9999 replicates.</p

Scatter plot representing the first two principal components of merged data sets of the three Kuwaiti groups and representative HGDP populations

<p>The first principal component value ranges from 3.505-3.537 and the second Component value ranges from 2.688-2.710 in multiple iterations of PCA. See Figure S6 for similar plot derived by including Yoruba population.</p

Plot of total amount of ROH versus total number of ROH segments in the three Kuwaiti groups and in representative HGDP populations.

<p>Kuwaiti groups exhibit a range of homozygosity showing characteristics of both consanguineous and non-consanguineous mating patterns. See Figure S5 for a representation for all of the Kuwait individuals in the background of all of the HGDP populations.</p

Length distributions of IBD and ROH segments shared among all of the Kuwaiti individuals (with F_roh > 0.0625 or F_ibd > 0.0625, as the case may be), and expected length distributions at different levels of inbreeding (6 or 9 generations since common ancestor).

<p>Considered are only those segments of length ≥ 1 cM. Assuming Haldanes’s recombination model, the length of segments should follow an exponential distribution with the mean as [1 / (2 × Number of generations since common ancestor)] in Morgans. The figure illustrates that the Kuwaiti population, as a whole, share a recent common ancestor within 6-9 generations. Figure S2 gives the distributions of IBD and ROH segments shared among individuals within each of the three Kuwaiti groups.</p

Improved estimates for four-year neuropsychological outcomes in children with isolated congenital heart defects.

<p>Abbreviations. SD  =  standard error. ADHD  =  attention deficit/hyperactivity disorder. CBCL  =  Child Behavior Checklist for ages 1.5 to 5 years. PDPs  =  pervasive developmental problems.</p