20 research outputs found
Role of Molecular Dipoles in Charge Transport across Large Area Molecular Junctions Delineated Using Isomorphic Self-Assembled Monolayers
Delineating
the role of dipoles in large area junctions that are
based on self-assembled monolayers (SAMs) is challenging due to molecular
tilt, surface defects, and interchain coupling among other features.
To mitigate SAM-based effects in study of dipoles, we investigated
tunneling rates across carboranesî¸isostructural molecules that
orient along the surface normal on Au (but bear different dipole moments)
without changing the thickness, packing density, or morphology of
the SAM. Using the Au-SAM//Ga<sub>2</sub>O<sub>3</sub>-EGaIn junction
(where â//â = physisorption, âââ
= chemisorption, and EGaIn is eutectic galliumâindium), we
observe that molecules with dipole moments oriented along the surface
normal (with dipole moment, <i>p</i> = 4.1D for both M9
and 1O2) gave lower currents than when the dipole is orthogonal (<i>p</i> = 1.1 D, M1) at Âą0.5 V applied bias. Similarly, from
transition voltage spectroscopy, the transition voltages, <i>V</i><sub>T</sub> (volt), are significantly different. (0.5,
0.43, and 0.4 V for M1, M9, and 1O2, respectively). We infer that
the magnitude and direction of a dipole moments significantly affect
the rate of charge transport across large area junctions with Î
log|J| â
0.4 per Debye. This difference is largely due to effect
of the dipole moment on the molecule-electrode coupling strength,
Î, hence effect of dipoles is likely to manifest in the contact
resistance, <i>J</i><sub>o</sub>, although in conformational
flexible molecules field-induced effects are expected
Structure of Aqueous Water Films on Textured âOH-Terminated Self-Assembled Monolayers
We report the thickness and interfacial
molecular structure of
thin (1â3 nm) aqueous films supported on hydroxyl-terminated
self-assembled monolayers over a silver substrate. The water film
structure is studied as a function of varying the monolayerâs
methylene chain lengths. Analysis techniques include ellipsometry,
contact angle, and polarization modulation reflection adsorption infrared
spectroscopy. The aqueous film thicknesses follow 4-mercaptobutanol
(4-MBU) > 11-mercaptoundecanol (11-MUD) > 6-mercaptohexanol
(6-MHE)
> 9-mercaptononanol (9-MNO). Water contact angle measurements across
the same surfaces are very similar; however, vibrational spectroscopic
analysis of the films shows that intermolecular bonding patterns of
D<sub>2</sub>O are significantly different from those of bulk D<sub>2</sub>O. This evokes unique interfacial molecular architectures
for each of these films. The structural differences depend on the
nature of the SAM structure and resulting waterâSAM interactions,
which are evident from PM-IRRAS data. Spectroscopic peak intensity
ratios of νÂ(OâD) modes suggest more asymmetric hydrogen-bonded
D<sub>2</sub>O character near 9-MNO surfaces, whereas 4-MDU, 6-MHE,
and 11-MUD surfaces exhibit increasingly symmetric hydrogen-bonded
D<sub>2</sub>O character. From this, we propose a model for film structure
Limits to the Effect of Substrate Roughness or Smoothness on the OddâEven Effect in Wetting Properties of <i>n</i>âAlkanethiolate Monolayers
This
study investigates the effect of roughness on interfacial
properties of an <i>n</i>-alkanethiolate self-assembled
monolayer (SAM) and uses hydrophobicity to demonstrate the existence
of upper and lower limits. This article also sheds light on the origin
of the previously unexplained gradual increase in contact angles with
increases in the size of the molecule making the SAM. We prepared
Au surfaces with a root-mean-square (RMS) roughness of âź0.2â0.5
nm and compared the wetting properties of <i>n</i>-alkanethiolate
(C<sub>10</sub>âC<sub>16</sub>) SAMs fabricated on these surfaces.
Static contact angles, θ<sub>s</sub>, formed between the SAM
and water, diethylene glycol, and hexadecane showed an oddâeven
effect irrespective of the solvent properties. The average differences
in subsequent SAM<sup>E</sup> and SAM<sup>O</sup> are Îθ<sub>s|<i>n </i>âŻââŻ(<i>n</i>+1)|</sub> â 1.7° (<i>n</i> = even) and Îθ<sub>s|<i>nâŻ</i>ââŻ(<i>n</i>+1)|</sub> â 3.1° (<i>n</i> = odd). A gradual increase
in θ<sub>s</sub> with increasing length of the molecule was
observed, with values ranging from water 104.7â110.7°
(overall Îθ<sub>s</sub> = 6.0° while for the evens
Îθ<sub>s</sub><sup>E</sup> = 4.4° and odds Îθ<sub>s</sub><sup>O</sup> = 3.5°) to diethylene glycol 72.9â80.4°
(overall Îθ<sub>s</sub> = 7.5° while for the evens
Îθ<sub>s</sub><sup>E</sup> = 2.9° and odds Îθ<sub>s</sub><sup>O</sup> = 2.4°) and hexadecane 40.4â49.4°
(overall Îθ<sub>s</sub> = 9.0° while for the evens
Îθ<sub>s</sub><sup>E</sup> = 3.7° and odds Îθ<sub>s</sub><sup>O</sup> = 2.1°). This article establishes that
the gradual increase in θ<sub>s</sub> with increasing molecular
size in SAMs is due to asymmetry in the zigzag oscillation in the
oddâeven effect. Comparison of the magnitude and proportion
differences in this asymmetry allows us to establish the reduction
in interfacial dispersive forces, due to increasing SAM crystallinity
with increasing molecular size, as the origin of this asymmetry. By
comparing the dependence of θ<sub>s</sub> on surface roughness
we infer that (i) RMS roughness â 1 nm is a theoretical limit
beyond which the oddâeven effect cannot be observed and (ii)
on a hypothetically flat surface the maximum difference in hydrophobicity,
as expressed in θ<sub>s</sub>, is âź3°
Table_7_Comprehensive identification and analysis of circRNAs during hickory (Carya cathayensis Sarg.) flower bud differentiation.xlsx
Flower bud differentiation represents a crucial transition from vegetative growth to reproductive development. Carya cathayensis (hickory) is an important economic species in China, with a long juvenile period that hinders its commercial development. In recent years, circular RNAs (circRNAs) have been widely studied and identified as sponges for miRNA regulation of mRNA expression. However, little is known regarding the role of circRNAs in flower buds. In this study, we sequenced circRNAs at three developmental stages (undifferentiated, differentiating, and fully differentiated) in both female and male buds. A total of 6,931 circRNAs were identified in the three developmental stages and 4,449 and 2,209 circRNAs were differentially expressed in female and male buds, respectively. Gene ontology demonstrated that many circRNA host genes participated in various processes, for example, cellular and intracellular pH regulation. Function annotation identified 46 differentially expressed circRNAs involved in flowering regulation, with 28 circRNAs found only in female buds, 4 found only in male buds, and 11 found in both female and male buds. A circRNA-miRNA-mRNA network was predicted based on 13 flowering-related circRNAs and their seven putative interacting miRNAs to describe the regulatory mechanism. Our preliminary results demonstrated a potential involvement of circRNA in bud differentiation. They provided a preliminary theoretical basis for how circRNA might participate in flower development in hickory, perhaps in woody plants.</p
Image_1_Comprehensive identification and analysis of circRNAs during hickory (Carya cathayensis Sarg.) flower bud differentiation.jpeg
Flower bud differentiation represents a crucial transition from vegetative growth to reproductive development. Carya cathayensis (hickory) is an important economic species in China, with a long juvenile period that hinders its commercial development. In recent years, circular RNAs (circRNAs) have been widely studied and identified as sponges for miRNA regulation of mRNA expression. However, little is known regarding the role of circRNAs in flower buds. In this study, we sequenced circRNAs at three developmental stages (undifferentiated, differentiating, and fully differentiated) in both female and male buds. A total of 6,931 circRNAs were identified in the three developmental stages and 4,449 and 2,209 circRNAs were differentially expressed in female and male buds, respectively. Gene ontology demonstrated that many circRNA host genes participated in various processes, for example, cellular and intracellular pH regulation. Function annotation identified 46 differentially expressed circRNAs involved in flowering regulation, with 28 circRNAs found only in female buds, 4 found only in male buds, and 11 found in both female and male buds. A circRNA-miRNA-mRNA network was predicted based on 13 flowering-related circRNAs and their seven putative interacting miRNAs to describe the regulatory mechanism. Our preliminary results demonstrated a potential involvement of circRNA in bud differentiation. They provided a preliminary theoretical basis for how circRNA might participate in flower development in hickory, perhaps in woody plants.</p
Table_14_Comprehensive identification and analysis of circRNAs during hickory (Carya cathayensis Sarg.) flower bud differentiation.xlsx
Flower bud differentiation represents a crucial transition from vegetative growth to reproductive development. Carya cathayensis (hickory) is an important economic species in China, with a long juvenile period that hinders its commercial development. In recent years, circular RNAs (circRNAs) have been widely studied and identified as sponges for miRNA regulation of mRNA expression. However, little is known regarding the role of circRNAs in flower buds. In this study, we sequenced circRNAs at three developmental stages (undifferentiated, differentiating, and fully differentiated) in both female and male buds. A total of 6,931 circRNAs were identified in the three developmental stages and 4,449 and 2,209 circRNAs were differentially expressed in female and male buds, respectively. Gene ontology demonstrated that many circRNA host genes participated in various processes, for example, cellular and intracellular pH regulation. Function annotation identified 46 differentially expressed circRNAs involved in flowering regulation, with 28 circRNAs found only in female buds, 4 found only in male buds, and 11 found in both female and male buds. A circRNA-miRNA-mRNA network was predicted based on 13 flowering-related circRNAs and their seven putative interacting miRNAs to describe the regulatory mechanism. Our preliminary results demonstrated a potential involvement of circRNA in bud differentiation. They provided a preliminary theoretical basis for how circRNA might participate in flower development in hickory, perhaps in woody plants.</p
Table_6_Comprehensive identification and analysis of circRNAs during hickory (Carya cathayensis Sarg.) flower bud differentiation.xlsx
Flower bud differentiation represents a crucial transition from vegetative growth to reproductive development. Carya cathayensis (hickory) is an important economic species in China, with a long juvenile period that hinders its commercial development. In recent years, circular RNAs (circRNAs) have been widely studied and identified as sponges for miRNA regulation of mRNA expression. However, little is known regarding the role of circRNAs in flower buds. In this study, we sequenced circRNAs at three developmental stages (undifferentiated, differentiating, and fully differentiated) in both female and male buds. A total of 6,931 circRNAs were identified in the three developmental stages and 4,449 and 2,209 circRNAs were differentially expressed in female and male buds, respectively. Gene ontology demonstrated that many circRNA host genes participated in various processes, for example, cellular and intracellular pH regulation. Function annotation identified 46 differentially expressed circRNAs involved in flowering regulation, with 28 circRNAs found only in female buds, 4 found only in male buds, and 11 found in both female and male buds. A circRNA-miRNA-mRNA network was predicted based on 13 flowering-related circRNAs and their seven putative interacting miRNAs to describe the regulatory mechanism. Our preliminary results demonstrated a potential involvement of circRNA in bud differentiation. They provided a preliminary theoretical basis for how circRNA might participate in flower development in hickory, perhaps in woody plants.</p
Table_5_Comprehensive identification and analysis of circRNAs during hickory (Carya cathayensis Sarg.) flower bud differentiation.xlsx
Flower bud differentiation represents a crucial transition from vegetative growth to reproductive development. Carya cathayensis (hickory) is an important economic species in China, with a long juvenile period that hinders its commercial development. In recent years, circular RNAs (circRNAs) have been widely studied and identified as sponges for miRNA regulation of mRNA expression. However, little is known regarding the role of circRNAs in flower buds. In this study, we sequenced circRNAs at three developmental stages (undifferentiated, differentiating, and fully differentiated) in both female and male buds. A total of 6,931 circRNAs were identified in the three developmental stages and 4,449 and 2,209 circRNAs were differentially expressed in female and male buds, respectively. Gene ontology demonstrated that many circRNA host genes participated in various processes, for example, cellular and intracellular pH regulation. Function annotation identified 46 differentially expressed circRNAs involved in flowering regulation, with 28 circRNAs found only in female buds, 4 found only in male buds, and 11 found in both female and male buds. A circRNA-miRNA-mRNA network was predicted based on 13 flowering-related circRNAs and their seven putative interacting miRNAs to describe the regulatory mechanism. Our preliminary results demonstrated a potential involvement of circRNA in bud differentiation. They provided a preliminary theoretical basis for how circRNA might participate in flower development in hickory, perhaps in woody plants.</p
Table_1_Comprehensive identification and analysis of circRNAs during hickory (Carya cathayensis Sarg.) flower bud differentiation.xlsx
Flower bud differentiation represents a crucial transition from vegetative growth to reproductive development. Carya cathayensis (hickory) is an important economic species in China, with a long juvenile period that hinders its commercial development. In recent years, circular RNAs (circRNAs) have been widely studied and identified as sponges for miRNA regulation of mRNA expression. However, little is known regarding the role of circRNAs in flower buds. In this study, we sequenced circRNAs at three developmental stages (undifferentiated, differentiating, and fully differentiated) in both female and male buds. A total of 6,931 circRNAs were identified in the three developmental stages and 4,449 and 2,209 circRNAs were differentially expressed in female and male buds, respectively. Gene ontology demonstrated that many circRNA host genes participated in various processes, for example, cellular and intracellular pH regulation. Function annotation identified 46 differentially expressed circRNAs involved in flowering regulation, with 28 circRNAs found only in female buds, 4 found only in male buds, and 11 found in both female and male buds. A circRNA-miRNA-mRNA network was predicted based on 13 flowering-related circRNAs and their seven putative interacting miRNAs to describe the regulatory mechanism. Our preliminary results demonstrated a potential involvement of circRNA in bud differentiation. They provided a preliminary theoretical basis for how circRNA might participate in flower development in hickory, perhaps in woody plants.</p
Table_12_Comprehensive identification and analysis of circRNAs during hickory (Carya cathayensis Sarg.) flower bud differentiation.xlsx
Flower bud differentiation represents a crucial transition from vegetative growth to reproductive development. Carya cathayensis (hickory) is an important economic species in China, with a long juvenile period that hinders its commercial development. In recent years, circular RNAs (circRNAs) have been widely studied and identified as sponges for miRNA regulation of mRNA expression. However, little is known regarding the role of circRNAs in flower buds. In this study, we sequenced circRNAs at three developmental stages (undifferentiated, differentiating, and fully differentiated) in both female and male buds. A total of 6,931 circRNAs were identified in the three developmental stages and 4,449 and 2,209 circRNAs were differentially expressed in female and male buds, respectively. Gene ontology demonstrated that many circRNA host genes participated in various processes, for example, cellular and intracellular pH regulation. Function annotation identified 46 differentially expressed circRNAs involved in flowering regulation, with 28 circRNAs found only in female buds, 4 found only in male buds, and 11 found in both female and male buds. A circRNA-miRNA-mRNA network was predicted based on 13 flowering-related circRNAs and their seven putative interacting miRNAs to describe the regulatory mechanism. Our preliminary results demonstrated a potential involvement of circRNA in bud differentiation. They provided a preliminary theoretical basis for how circRNA might participate in flower development in hickory, perhaps in woody plants.</p