Scanning Probe Investigations of Multidentate Thiol and Spatially Confined Porphyrin Nanoassemblies using Nanoscale Lithography

Approaches to prepare spatially selective surfaces were developed in this dissertation for constructing nanopatterns of organic thin film materials. Nanoscale surface patterns were prepared using immersion particle lithography and scanning probe lithography combined with organothiol chemistry. Organic thin films and nanomaterials can be patterned with tunable periodicities and designed shapes by selecting the diameter of mesospheres used as surface masks or scanning probe lithography, respectively. The surface platforms of well-defined nanopatterns are ideal for high resolution investigations using scanning probe microscopy (SPM). Local measurements of surface properties and conductive properties combined with nanolithography were accomplished at the molecular level. Sample characterizations were accomplished with selected modes of SPM. Scanning probe studies can be used to probe the morphological and physical properties of samples, when spatially confined nanomaterials are prepared. Atomic force microscopy (AFM) can be used to analyze many types of samples in ambient and liquid environments. Arrays of nanostructures formed with newly designed molecules and porphyrins were fabricated using the spatial selectivity of chemical patterns prepared with nanolithography. The designed nanopatterns were evaluated for morphological details and physical properties. A newly designed bidentate organosulfur compound, i.e. 16-[3,5-bis(mercaptomethyl)phenoxy] hexadecanoic acid (BMPHA), was selected for study. The solution phase self-assembly onto Au(111) was investigated with scanning probe-based nanolithography and particle lithography. The two thiol groups of BMPHA were specially designed as surface linkers for improved stability. The orientation of BMPHA on Au(111) was investigated by referencing the heights of n-alkanethiols as an in situ molecular ruler. Protocols for patterning porphyrin nanostructures i.e. nanodots and nanorods on Au(111) were developed based on protocols with immersion particle lithography. Porphyrins with and without a central metal ion, 5,10,15,20-tetraphenyl-21H,23H-porphine (TPP) and 5,10,15,20-tetraphenyl-21H,23H-porphine cobalt(II) (TPC) were patterned using immersion particle lithography. Individual nanorods and nanodots of porphyrins were spatially isolated into well-defined, nanoscale arrangements directed by a template film of a nanopatterned thiol monolayer. The conductivity of the nanostructures of the porphyrins was evaluated using conductive probe-atomic force microscopy (CP-AFM). The studies evaluate the applicability of nanolithography for preparing surface platforms for the measurements of morphological and physical properties at the nanoscale

A Review of Smart Materials in Tactile Actuators for Information Delivery

As the largest organ in the human body, the skin provides the important sensory channel for humans to receive external stimulations based on touch. By the information perceived through touch, people can feel and guess the properties of objects, like weight, temperature, textures, and motion, etc. In fact, those properties are nerve stimuli to our brain received by different kinds of receptors in the skin. Mechanical, electrical, and thermal stimuli can stimulate these receptors and cause different information to be conveyed through the nerves. Technologies for actuators to provide mechanical, electrical or thermal stimuli have been developed. These include static or vibrational actuation, electrostatic stimulation, focused ultrasound, and more. Smart materials, such as piezoelectric materials, carbon nanotubes, and shape memory alloys, play important roles in providing actuation for tactile sensation. This paper aims to review the background biological knowledge of human tactile sensing, to give an understanding of how we sense and interact with the world through the sense of touch, as well as the conventional and state-of-the-art technologies of tactile actuators for tactile feedback delivery

Nanoscale lithography mediated by surface self-assembly of 16-[3,5-bis(mercaptomethyl)phenoxy]hexadecanoic acid on Au(111) investigated by scanning probe microscopy

The solution-phase self-assembly of bidentate 16-[3,5-bis(mercaptomethyl) phenoxy]hexadecanoic acid (BMPHA) on Au(111) was studied using nano-fabrication protocols with scanning probe nanolithography and immersion particle lithography. Molecularly thin films of BMPHA prepared by surface self-assembly have potential application as spatially selective layers in sensor designs. Either monolayer or bilayer films of BMPHA can be formed under ambient conditions, depending on the parameters of concentration and immersion intervals. Experiments with scanning probe-based lithography (nanoshaving and nanografting) were applied to measure the thickness of BMPHA films. The thickness of a monolayer and bilayer film of BMPHA on Au(111) were measured in situ with atomic force microscopy using n-octadecanethiol as an internal reference. Scanning probe-based nanofabrication provides a way to insert nanopatterns of a reference molecule of known dimensions within a matrix film of unknown thickness to enable a direct comparison of heights and surface morphology. Immersion particle lithography was used to prepare a periodic arrangement of nanoholes within films of BMPHA. The nanoholes could be backfilled by immersion in a SAM solution to produce nanodots of n-octadecanethiol surrounded by a film of BMPHA. Test platforms prepared by immersion particle lithography enables control of the dimensions of surface sites to construct supramolecular assemblies

A preliminary evaluation of targeted nanopore sequencing technology for the detection of Mycobacterium tuberculosis in bronchoalveolar lavage fluid specimens

ObjectiveTo evaluate the efficacy of targeted nanopore sequencing technology for the detection of Mycobacterium tuberculosis(M.tb.) in bronchoalveolar lavage fluid(BALF) specimens.MethodsA prospective study was used to select 58 patients with suspected pulmonary tuberculosis(PTB) at Henan Chest Hospital from January to October 2022 for bronchoscopy, and BALF specimens were subjected to acid-fast bacilli(AFB) smear, Mycobacterium tuberculosis MGIT960 liquid culture, Gene Xpert MTB/RIF (Xpert MTB/RIF) and targeted nanopore sequencing (TNS) for the detection of M.tb., comparing the differences in the positive rates of the four methods for the detection of patients with different classifications.ResultsAmong 58 patients with suspected pulmonary tuberculosis, there were 48 patients with a final diagnosis of pulmonary tuberculosis. Using the clinical composite diagnosis as the reference gold standard, the sensitivity of AFB smear were 27.1% (95% CI: 15.3-41.8); for M.tb culture were 39.6% (95% CI: 25.8-54.7); for Xpert MTB/RIF were 56.2% (95% CI: 41.2-70.5); for TNS were 89.6% (95% CI: 77.3-96.5). Using BALF specimens Xpert MTB/RIF and/or M.tb. culture as the reference standard, TNS showed 100% (30/30) sensitivity. The sensitivity of NGS for pulmonary tuberculosis diagnosis was significantly higher than Xpert MTB/RIF, M.tb. culture, and AFB smear. Besides, P values of <0.05 were considered statistically significant.ConclusionUsing a clinical composite reference standard as a reference gold standard, TNS has the highest sensitivity and consistency with clinical diagnosis, and can rapidly and efficiently detect PTB in BALF specimens, which can aid to improve the early diagnosis of suspected tuberculosis patients

Genotypes and haplotypes of the VEGF gene and survival in locally advanced non-small cell lung cancer patients treated with chemoradiotherapy

<p>Abstract</p> <p>Background</p> <p>Vascular endothelial growth factor (VEGF) is a major mediator of angiogenesis involving in carcinogenesis, including lung cancer. We hypothesized that <it>VEGF </it>polymorphisms may affect survival outcomes among locally advanced non-small cell lung cancer (LA-NSCLC) patients.</p> <p>Methods</p> <p>We genotyped three potentially functional <it>VEGF </it>variants [-460 T > C (rs833061), -634 G > C (rs2010963), and +936 C > T (rs3025039)] and estimated haplotypes in 124 Caucasian patients with LA-NSCLC treated with definitive radiotherapy. We used Kaplan-Meier log-rank tests, and Cox proportional hazard models to evaluate the association between <it>VEGF </it>variants and overall survival (OS).</p> <p>Results</p> <p>Gender, Karnofsky's performance scores (KPS) and clinical stage seemed to influence the OS. The variant C genotypes were independently associated with significantly improved OS (CT+CC vs. TT: adjusted hazard ratio [HR] = 0.58; 95% confidence interval [CI] = 0.37-0.92, <it>P </it>= 0.022), compared with the <it>VEGF </it>-460 TT genotype.</p> <p>Conclusions</p> <p>Our study suggests that <it>VEGF </it>-460 C genotypes may be associated with a better survival of LA-NSCLC patients after chemoradiotherapy. Large studies are needed to confirm our findings.</p

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Nanoscale Lithography Mediated by Surface Self-Assembly of 16-[3,5-Bis(Mercaptomethyl)phenoxy]hexadecanoic Acid on Au(111) Investigated by Scanning Probe Microscopy

The solution-phase self-assembly of bidentate 16-[3,5-bis(mercapto-methyl)phenoxy]hexadecanoic acid (BMPHA) on Au(111) was studied using nano-fabrication protocols with scanning probe nanolithography and immersion particle lithography. Molecularly thin films of BMPHA prepared by surface self-assembly have potential application as spatially selective layers in sensor designs. Either monolayer or bilayer films of BMPHA can be formed under ambient conditions, depending on the parameters of concentration and immersion intervals. Experiments with scanning probe-based lithography (nanoshaving and nanografting) were applied to measure the thickness of BMPHA films. The thickness of a monolayer and bilayer film of BMPHA on Au(111) were measured in situ with atomic force microscopy using n-octadecanethiol as an internal reference. Scanning probe-based nanofabrication provides a way to insert nanopatterns of a reference molecule of known dimensions within a matrix film of unknown thickness to enable a direct comparison of heights and surface morphology. Immersion particle lithography was used to prepare a periodic arrangement of nanoholes within films of BMPHA. The nanoholes could be backfilled by immersion in a SAM solution to produce nanodots of n-octadecanethiol surrounded by a film of BMPHA. Test platforms prepared by immersion particle lithography enables control of the dimensions of surface sites to construct supramolecular assemblies

Effects of Vehicle Air Temperature on Drivers’ Cognitive Abilities Based on EEG

Vehicle air temperature affects drivers’ physiology, psychology, and cognitive abilities. However, the effects are difficult to quantify, especially for jobs related to driving tasks. In this research, 10 male subjects were directly exposed to four different vehicle air temperatures of 20, 23, 26, and 30 °C for 160 min. They were asked to perform cognitive tasks and subjective questionnaires, and 16 channels of EEG signals were monitored in a vehicle cabin. Based on the assessment of the EEG characteristics, the impacts of vehicle air temperature on cognitive abilities and EEG were investigated. The results showed that the cognitive ability of drivers decreased with the rising of the ambient temperature. The subjective questionnaire scores for thermal sensation, thermal comfort and brain load increased as ambient temperature rose; meanwhile, the scores for environmental acceptance, job satisfaction and willingness to work declined. As the ambient temperature rose, the normalized power of θ activity and α activity elevated, and the vigilance and frontal EEG asymmetry decreased. At 20 °C, the completion time of cognitive ability test was the shortest, the number of errors was the smallest, and the drivers could maintain high cognitive ability. At this time, the β activity component of the EEG signal increased, and the level of alertness (AL) and prefrontal asymmetry (FEA) also increased. At 23 °C, drivers’ subjective thermal comfort reached its peak: the EEG wavelet entropy values of the two segments before and after the experiment were the largest, and the wavelet entropy difference was also the largest. A suitable vehicle air temperature aroused β activity and motivation, increased driver alertness and thus enhanced cognitive performance. Therefore, to achieve high cognitive ability and thermal comfort, the vehicle air temperature should be maintained between 20 °C and 23 °C. The research results can provide a reference for the design standards of vehicle air temperature and improve the safety of driving

Conductive-probe measurements with nanodots of free-base and metallated porphyrins

© 2016 The conductive properties of nanodots of model porphyrins were investigated using conductive-probe atomic force microscopy (CP-AFM). Porphyrins provide excellent models for preparing surface structures that can potentially be used as building blocks for devices. The conjugated, planar structure of porphyrins offers opportunities for tailoring the electronic properties. Two model porphyrins were selected for studies, 5,10,15,20-tetraphenyl-21H,23H-porphine cobalt(II) (TPC) and its metal-free analog 5,10,15,20-tetraphenyl-21H,23H-porphine (TPP). Nanodots of TPP and TPC were prepared within a dodecanethiol resist on gold using particle lithography. The nanopatterned surfaces exhibit millions of reproducible test structures of porphyrin nanodots. The porphyrin nanodots have slight differences in dimensions at the nanoscale, to enable size-dependent measurements of conductive properties. The size of the nanodots corresponds to ∼5–7 layers of porphyrin. The conductivity along the vertical direction of the nanodots was measured by applying a bias voltage between the gold surface and a metal-coated AFM cantilever. The TPP nanodots exhibited semi-conductive profiles while the TPC nanodots exhibited profiles that are typical of a conductive film or molecular wire. The engineered nanostructures of porphyrins provide an effective platform for investigation and measurement of conductive properties

Characterization of Microchannel Replicability of Injection Molded Electrophoresis Microfluidic Chips

Microfluidic chips have been widely applied in biochemical analysis, DNA sequencing, and disease diagnosis due to their advantages of miniaturization, low consumption, rapid analysis, and automation. Injection molded microfluidic chips have attracted great attention because of their short processing time, low cost, and mass production. The microchannel is the critical element of a microfluidic chip, and thus the microchannel replicability directly affects the performance of the microfluidic chip. In the current paper, a new method is proposed to evaluate the replicability of the microchannel profile via the root mean square value of the actual profile curve and the ideal profile curve of the microchannel. To investigate the effects of injection molding parameters (i.e., mold temperature, melting temperature, holding pressure, holding time, and injection rate) on microchannel replicability, a series of single-factor experiments were carried out. The results showed that, within the investigated experimental range, the increase of mold temperature, melt temperature, holding pressure, holding time, and injection rate could improve microchannel replicability accuracy. Specifically, the microchannels along the flow direction of the polymer melt were significantly affected by the mold temperature and melt temperature. Moreover, the replicability of the microchannel was influenced by the distance from the injection gate. The effect of microchannel replication on electrophoresis was demonstrated by a protein electrophoresis experiment