Layered GaGeTe Thermoelectric Materials with Multivalley Conduction Bands

GaGeTe is interesting as a thermoelectric material since it has a layered tetradymite-like structure similar to state-of-the-art Bi2Te3. However, the electronic structure, electrical transport properties, and their rationalization in GaGeTe are rarely studied. In this study, we focus on the electronic structure and electrical transport properties of GaGeTe by combining theory and experiment. Experimentally, intrinsic p-type thermoelectric properties of pristine and Ag-doped GaGeTe polycrystalline samples are reported and found to be anisotropic due to the layered structure. Electronic structure calculation reveals GaGeTe as a semiconductor with a moderate band gap, consistent with the experimental transport properties showing no obvious bipolar effect. Based on the electronic structure, the Boltzmann transport theory is applied to calculate transport properties, leading to an excellent agreement with the experimental data of p-type GaGeTe. Strikingly, n-type electrical transport properties are predicted to be much more favorable than the p-type counterparts, which can be rationalized by the multivalley conduction bands with a primary contribution from a nontrivial 6-fold valley-degenerate conduction band. A peak zT of ∼0.7 at 800 K is estimated for n-type GaGeTe using the experimental lattice thermal conductivity of the pristine sample. We thereby expect GaGeTe to be a promising thermoelectric material if n-type doping is achievable. This work provides insights into the electronic structure and electrical transport for the further development of GaGeTe thermoelectrics

Frequencies of derived haplotypes (≥1%) from six examined polymorphisms of <i>RAC1</i> gene in cases and controls.

<p>Frequencies of derived haplotypes (≥1%) from six examined polymorphisms of <i>RAC1</i> gene in cases and controls.</p

Schematic presentation of the structure of RAC1 gene indicating locations of the analyzed variants (rs836488, rs702482, rs10951982, rs702483, rs6954996, and rs9374).

<p>The RAC1 gene consists of 7 exons (I-VII).</p

Linkage disequilibrium results among the six SNPs in <i>RAC1</i> gene.

<p>Linkage disequilibrium results among the six SNPs in <i>RAC1</i> gene.</p

The demographic characteristics of cases and controls.

<p>The demographic characteristics of cases and controls.</p

Representative figures of direct sequencing for the six SNPs of <i>RAC1</i> gene.

<p>(A) rs836488, (B) rs702482, (C) rs10951982, (D) rs702483, (E) rs6954996, and (F) rs9374. Allelic variants were indicated by boxes.</p

Stratification analysis of <i>RAC1</i> polymorphisms in renal transplant recipients and healthy subjects.

<p>Stratification analysis of <i>RAC1</i> polymorphisms in renal transplant recipients and healthy subjects.</p

Genotype and allele distribution of <i>RAC1</i> gene in renal transplant recipients and healthy subjects.

<p>Genotype and allele distribution of <i>RAC1</i> gene in renal transplant recipients and healthy subjects.</p

Data_Sheet_1_Effects of intestinal microbiota on pharmacokinetics of cyclosporine a in rats.docx

BackgroundIntestinal microbiota has been confirmed to influencing the pharmacokinetic processes of a variety of oral drugs. However, the pharmacokinetic effects of the gut microbiota on cyclosporine A, a drug with a narrow therapeutic window, remain to be studied.MethodTwenty-one rats were randomly divided into three groups: (a) control group (CON), (b) antibiotic treatment group (ABT) and (c) fecal microbe transplantation group (FMT). The ABT group was administrated with water containing multiple antibiotics to deplete microorganisms. FMT was with the same treatment, followed by oral administration of conventional rat fecal microorganisms for normalization.ResultThe bioavailability of CSA increased by 155.6% after intestinal microbes were consumed by antibiotics. After intestinal microbiota reconstruction by fecal transplantation, the increased bioavailability was significantly reduced and basically returned to the control group level. Changes in gut microbiota alter the protein expression of CYP3A1, UGT1A1 and P-gp in liver. The expressions of these three proteins in ABT group were significantly lower than those in CON and FMT groups. The relative abundance of Alloprevolleta and Oscillospiraceae UCG 005 was negatively correlated with CSA bioavailability while the relative abundance of Parasutterella and Eubacterium xylanophilum group was negatively correlated with CSA bioavailability.ConclusionIntestinal microbiota affects the pharmacokinetics of CSA by regulating the expression of CYP3A1, UGT1A1 and P-GP.</p

Image_1_Effects of intestinal microbiota on pharmacokinetics of cyclosporine a in rats.TIF

BackgroundIntestinal microbiota has been confirmed to influencing the pharmacokinetic processes of a variety of oral drugs. However, the pharmacokinetic effects of the gut microbiota on cyclosporine A, a drug with a narrow therapeutic window, remain to be studied.MethodTwenty-one rats were randomly divided into three groups: (a) control group (CON), (b) antibiotic treatment group (ABT) and (c) fecal microbe transplantation group (FMT). The ABT group was administrated with water containing multiple antibiotics to deplete microorganisms. FMT was with the same treatment, followed by oral administration of conventional rat fecal microorganisms for normalization.ResultThe bioavailability of CSA increased by 155.6% after intestinal microbes were consumed by antibiotics. After intestinal microbiota reconstruction by fecal transplantation, the increased bioavailability was significantly reduced and basically returned to the control group level. Changes in gut microbiota alter the protein expression of CYP3A1, UGT1A1 and P-gp in liver. The expressions of these three proteins in ABT group were significantly lower than those in CON and FMT groups. The relative abundance of Alloprevolleta and Oscillospiraceae UCG 005 was negatively correlated with CSA bioavailability while the relative abundance of Parasutterella and Eubacterium xylanophilum group was negatively correlated with CSA bioavailability.ConclusionIntestinal microbiota affects the pharmacokinetics of CSA by regulating the expression of CYP3A1, UGT1A1 and P-GP.</p