Adsorptive Desulfurization of Condensate Contains Aromatic Compounds Using a Commercial Molecular Sieve.

This study is undertaken to evaluate the potential of a commercial molecular sieve to remove diverse sulfur compounds from condensate with high aromatic on an industrial scale. For the first part of this study, the adsorbent is characterized in detail using inductively coupled plasma optical emission spectroscopy, X-ray diffraction, field-emission scanning electron microscopy, and Brunauer-Emmett-Teller analysis. For the second part, dynamic breakthrough experiments on an industrial scale are performed to assess the dynamic adsorption performance of a commercial molecular sieve. Dynamic experiments show that the adsorbent effectively removes the sulfur compound from condensate that has approximately 900 ppmw S. In more detail, this commercial molecular sieve selectively desulfurizes condensate to about 12 ppmw S, and this is achieved when the concentration of non-sulfur aromatic is greater than 15 times higher than the total sulfur. As regeneration is a crucial part of the continuous adsorption-regeneration cycling process, the final part of this study is focused on finding a desorption method to avoid a sulfur concentration peak in tail gas.

Stoichiometry modulates the optoelectronic functionality of zinc phosphide (Zn3-xP2+x).

Predictive synthesis-structure-property relationships are at the core of materials design for novel applications. In this regard, correlations between the compositional stoichiometry variations and functional properties are essential for enhancing the performance of devices based on these materials. In this work, we investigate the effect of stoichiometry variations and defects on the structural and optoelectronic properties of monocrystalline zinc phosphide (Zn3P2), a promising compound for photovoltaic applications. We use experimental methods, such as electron and X-ray diffraction and Raman spectroscopy, along with density functional theory calculations, to showcase the favorable creation of P interstitial defects over Zn vacancies in P-rich and Zn-poor compositional regions. Photoluminescence and absorption measurements show that these defects create additional energy levels at about 180 meV above the valence band. Furthermore, they lead to the narrowing of the bandgap, due to the creation of band tails in the region of around 10-20 meV above the valence and below the conduction band. The ability of zinc phosphide to form off-stoichiometric compounds provides a new promising opportunity for tunable functionality that benefits applications. In that regard, this study is crucial for the further development of zinc phosphide and its application in optoelectronic and photovoltaic devices, and should pave the way for defect engineering in this kind of material.

Nanoscale Growth Initiation as a Pathway to Improve the Earth-Abundant Absorber Zinc Phosphide.

Growth approaches that limit the interface area between layers to nanoscale regions are emerging as a promising pathway to limit the interface defect formation due to mismatching lattice parameters or thermal expansion coefficient. Interfacial defect mitigation is of great interest in photovoltaics as it opens up more material combinations for use in devices. Herein, an overview of the vapor-liquid-solid and selective area epitaxy growth approaches applied to zinc phosphide (Zn3P2), an earth-abundant absorber material, is presented. First, we show how different morphologies, including nanowires, nanopyramids, and thin films, can be achieved by tuning the growth conditions and growth mechanisms. The growth conditions are also shown to greatly impact the defect structure and composition of the grown material, which can vary considerably from the ideal stoichiometry (Zn3P2). Finally, the functional properties are characterized. The direct band gap could accurately be determined at 1.50 ± 0.1 eV, and through complementary density functional theory calculations, we can identify a range of higher-order band gap transitions observed through valence electron energy loss spectroscopy and cathodoluminescence. Furthermore, we outline the formation of rotated domains inside of the material, which are a potential origin of defect transitions that have been long observed in zinc phosphide but not yet explained. The basic understanding provided reinvigorates the potential use of earth-abundant II-V semiconductors in photovoltaic technology. Moreover, the transferrable nanoscale growth approaches have the potential to be applied to other material systems, as they mitigate the constraints of substrate-material combinations causing interface defects.

Clinical, laboratory data and outcomes of 17 Iranian citrullinemia type 1 patients: Identification of five novel ASS1 gene mutations.

Citrullinemia type 1 is an autosomal recessive metabolic disease caused by ASS1 gene mutations encoding argininosuccinic acid synthetase enzyme which is within the pathway of arginine and nitric oxide biosynthesis. Disease confirmation was done by ASS1 gene mutation analysis using next-generation sequencing, DNA Sanger sequencing. The study group was 17 citrullinemia type 1 patients from 10 unrelated families referred to Iranian National Society for Study on Inborn Errors of Metabolism's clinic between 2008 and 2020. Clinical, laboratory, and molecular data were retrospectively evaluated. Eleven different ASS1 gene mutations were detected in 13 (76%) of 17 neonatal, three (18%) of 17 late infantile, and one (6%) of 17 asymptomatic patients. Severe developmental delay and intractable seizures despite metabolic control was outcome of neonatal form survivor. Two late infantile form patients live metabolically controlled with quite normal performance. DNA mutations are as follows: seven missense, one nonsense, and two insertion/deletion mutations in 12, two, and three patients, respectively. Five novel mutations were detected including a homozygous GG deletion in exon 12 (c.790_791delGG;p.Gly264Profs*3) and a homozygous mutation in exon 7 (c.440C>T; p.Met147Thr), both causing infantile (late onset) form; a homozygous mutation in exon 6 (c.1130T>C; p.Met376Thr) causing neonatal form; two compound heterozygote mutations in exon 14 (c.1167_1168insC:p.Gly390Argfs*22& c.1186T>A; p.Ser396Thr) causing asymptomatic form. Five (38%) patients with classic neonatal form had mutation in exon 14 of ASS1 (c.1168G>A; p.Gly390Arg). Classic neonatal was the most common form of disease in Iranian-studied patients and homozygote c.1168G>A was the most frequent ASS1 gene mutation. Global neonatal screening for citrullinemia type 1 in Iran is recommended and certain mutations can be used for screening severe form in this population.

Showcasing the optical properties of monocrystalline zinc phosphide thin films as an earth-abundant photovoltaic absorber.

Zinc phosphide, Zn3P2, is a semiconductor with a high absorption coefficient in the spectral range relevant for single junction photovoltaic applications. It is made of elements abundant in the Earth's crust, opening up a pathway for large deployment of solar cell alternatives to the silicon market. Here we provide a thorough study of the optical properties of single crystalline Zn3P2 thin films grown on (100) InP by molecular beam epitaxy. The films are slightly phosphorus-rich as determined by Rutherford backscattering. We elucidate two main radiative recombination pathways: one transition at approximately 1.52 eV attributed to zone-center band-to-band electronic transitions; and a lower-energy transition observed at 1.3 eV to 1.4 eV attributed to a defect band or band tail related recombination mechanisms. We believe phosphorus interstitials are likely at the origin of this band.

The impact of the HLA DQB1 gene and amino acids on the development of narcolepsy.

INTRODUCTION: Narcolepsy is a chronic neurological and a genetic disorder of autoimmune origin, which is characterized by five main symptoms, including excessive day time sleepiness, sudden loss of muscle tone or cataplexy, sleep paralysis, hypnagogic hallucinations, and disturbed nocturnal sleep. While there are several diagnostic tests for Narcolepsy such as MSLT (mean sleep latency test), polysomnography and low range of hypocretin in cerebrospinal fluid (CSF), sensitivity and specificity in these methodologies are not sufficient enough. Therefore, methods with higher sensitivity for the accurate diagnosis and confirmation of the disease are necessary. METHODS: According to the infrequent prevalence of narcolepsy disease, we scheduled a case-control association study with 20 narcoleptic patients and 150 healthy individuals in a high-resolution HLA typing procedure employing SSP-PCR. RESULTS: Our study demonstrates that the DQB1*06:02 allele provides the highest susceptibility with absolute risk of 0.13%, for Narcolepsy (P = 1x10-14, RR = 60.5, PcPPV = 0.13%), while, HLA-DQB1* 03:05 allele presents protection to Narcolepsy (P = 1x10-4, PcPPV = 3.19x10-4%). Furthermore, for the first time, the AA analysis displayed that AA serine182 and threonine185 located on epitope of DQß1 chain receptor (DQB1Ser182,Thr185) present significant susceptibility for Narcolepsy (Pc= 87.03 × 10-13, PcPPV = 0.024%) while, asparagine182 located on epitope of DQß1 protein receptor (DQB1Asn182) confers the highest protection against development of Narcolepsy (Pc= 2.16 × 10-5, PcPPV = 0.0012%). CONCLUSION: Thus, this can be proposed that the polymorphic differences in the epitope of the HLA receptor could contribute to their differential association with the Narcolepsy in Iranian population.

Contribution of HLA class II genes, DRB4*01:01, DRB1*07:01, and DQB1*03:03:2 to clinical features of Vitiligo disease in Iranian population.

BACKGROUND: Vitiligo is a multifactorial depigmentation condition, which is due to skin melanocyte destruction. Increased expression of HLA class II genes in patients with pre-lesions of Vitiligo suggests a crucial role for the participation of immune response in Vitiligo development. Recent studies progressively focused on HLA-DRB1 and DQB1 genes. In this study, we have evaluated the association and role of HLA-DRB4*01:01, -DRB1*07:01, and -DQB1*03:03:2 genes in different clinical subtypes of Vitiligo in the Iranian population. METHODS: First, Genomic DNA from peripheral blood of 125 unrelated Vitiligo patients and 100 unrelated healthy controls were extracted through the salting-out method. Then, HLA class II genotyping was performed using the sequence-specific primer PCR method. Finally, the clinical relevance of the testing for these genotypes was evaluated by applying the PcPPV (prevalence-corrected positive predictive value) formula. RESULTS: Our results indicated the positive associations of DRB4*01:01 and DRB1*07:01 allelic genes with early-onset Vitiligo (p = 0.024 and 0.022, respectively). DRB4*01:01 also showed strong protection against late-onset Vitiligo (p = 0.0016, RR = 0.360). Moreover, our data revealed that the DRB1*07:01 increases the susceptibility to Sporadic Vitiligo (p = 0.030, RR = 1.702). Furthermore, our findings proposed that elevated vulnerability of Vitiligo patients due to DRB4*01:01 and DRB1*07:01 alleles maybe is correlated with the presence of amino acid Arginine at position 71 at pocket 4 on the antigen-binding site of the HLA-DRB1 receptor. CONCLUSION: Our findings on different subtypes of Vitiligo suggest that, despite a more apparent autoimmune involvement, a non-autoimmune nature for the etiology of Vitiligo should also be considered.

Raman tensor of zinc-phosphide (Zn3P2): from polarization measurements to simulation of Raman spectra.

Zinc phosphide (Zn3P2) is a II-V compound semiconductor with promising photovoltaic and thermoelectric applications. Its complex structure is susceptible to facile defect formation, which plays a key role in further optimization of the material. Raman spectroscopy can be effectively used for defect characterization. However, the Raman tensor of Zn3P2, which determines the intensity of Raman peaks and anisotropy of inelastic light scattering, is still unknown. In this paper, we use angle-resolved polarization Raman measurements on stoichiometric monocrystalline Zn3P2 thin films to obtain the Raman tensor of Zn3P2. This has allowed determination of the Raman tensor elements characteristic for the A1g, B1g and B2g vibrational modes. These results have been compared with the theoretically obtained Raman tensor elements and simulated Raman spectra from the lattice-dynamics calculations using first-principles force constants. Excellent agreement is found between the experimental and simulated Raman spectra of Zn3P2 for various polarization configurations, providing a platform for future characterization of the defects in this material.

Rotated domains in selective area epitaxy grown Zn3P2: formation mechanism and functionality.

Zinc phosphide (Zn3P2) is an ideal absorber candidate for solar cells thanks to its direct bandgap, earth-abundance, and optoelectronic characteristics, albeit it has been insufficiently investigated due to limitations in the fabrication of high-quality material. It is possible to overcome these factors by obtaining the material as nanostructures, e.g. via the selective area epitaxy approach, enabling additional strain relaxation mechanisms and minimizing the interface area. We demonstrate that Zn3P2 nanowires grow mostly defect-free when growth is oriented along the [100] and [110] of the crystal, which is obtained in nanoscale openings along the [110] and [010] on InP(100). We detect the presence of two stable rotated crystal domains that coexist in the structure. They are due to a change in the growth facet, which originates either from the island formation and merging in the initial stages of growth or lateral overgrowth. These domains have been visualized through 3D atomic models and confirmed with image simulations of the atomic scale electron micrographs. Density functional theory simulations describe the rotated domains' formation mechanism and demonstrate their lattice-matched epitaxial relation. In addition, the energies of the shallow states predicted closely agree with transition energies observed by experimental studies and offer a potential origin for these defect transitions. Our study represents an important step forward in the understanding of Zn3P2 and thus for the realisation of solar cells to respond to the present call for sustainable photovoltaic technology.

Pharmacogenetic and Association Studies on the Influence of HLA Alleles and Rivastigmine on the Iranian Patients with Late-Onset Alzheimer's Disease.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder affecting cognitive function. A number of allelic genes from HLA complex have shown variable associations with AD in different populations. In this study, we investigated the association of DQB1*06:00/x, DRB1*04:00/x, DRB1*15:00/x, and B*07:00/x genotypes with AD and their relevance to the efficacy of rivastigmine treatment in the Iranian population. Our findings suggest that DQB1*06:00/x genotype offers strong protection against AD (P = 0.0074), while B*07:00/x genotype imposes a significant susceptibility for sporadic Alzheimer's disease (SAD) (P = 0.009). Interestingly, B*07:00/x genotype does not show any apparent associations with familial Alzheimer's disease (FAD). Our studies also suggest a pharmacogenetic relationship between drug treatment and presence of a particular genotype in the Iranian LOAD patient population. The Clinical Dementia Rating analysis showed that LOAD patients carrying DRB1*04:00/x genotype tend to display a downward trend in the disease severity and symptoms after 2-year follow-up with rivastigmine treatment. Moreover, in our total patient population, the carriers of DQB1*06:00/x and B*07:00/x alleles have better and worse responses to rivastigmine respectively. We also measured the clinical relevance of the testing for these genotypes employing prevalence-corrected positive predictive value (PcPPV) formula. The PcPPV of testing for DQB1*06:00/x in the Iranian LOAD patients was 1.17% which means that people carrying this genotype have half of the probability of the absolute risk for developing LOAD, whereas the PcPPV of testing for B*07:00/x was 4.45% for SAD, which can be interpreted as a doubling chance for developing LOAD among the Iranian population carrying this genotype. These results also suggest that DQß1 peptide containing positively charged AAs histidine30 and arginine55 and HLA class I ß chain containing negatively charges aspartic acid114 and glutamic acid45,152 in their binding groove plays important roles in protection against and susceptibility for LOAD respectively.

Towards defect-free thin films of the earth-abundant absorber zinc phosphide by nanopatterning.

Large-scale deployment of thin-film photovoltaics will be facilitated through earth-abundant components. Herein, selective area epitaxy and lateral overgrowth epitaxy are explored for the growth of zinc phosphide (Zn3P2), a promising earth-abundant absorber. The ideal growth conditions are elucidated, and the nucleation of single-crystal nanopyramids that subsequently evolve towards coalesced thin-films is demonstrated. The zinc phosphide pyramids exhibit room temperature bandgap luminescence at 1.53 eV, indicating a high-quality material. The electrical properties of zinc phosphide and the junction with the substrate are assessed by conductive atomic force microscopy on n-type, p-type and intrinsic substrates. The measurements are consistent with the p-type characteristic of zinc phosphide. Overall, this constitutes a new, and transferrable, approach for the controlled and tunable growth of high-quality zinc phosphide, a step forward in the quest for earth-abundant photovoltaics.

Raman spectroscopy and lattice dynamics calculations of tetragonally-structured single crystal zinc phosphide (Zn3P2) nanowires.

Earth-abundant and low-cost semiconductors, such as zinc phosphide (Zn3P2), are promising candidates for the next generation photovoltaic applications. However, synthesis on commercially available substrates, which favors the formation of defects, and controllable doping are challenging drawbacks that restrain device performance. Better assessment of relevant properties such as structure, crystal quality and defects will allow faster advancement of Zn3P2, and in this sense, Raman spectroscopy can play an invaluable role. In order to provide a complete Raman spectrum reference of Zn3P2, this work presents a comprehensive analysis of vibrational properties of tetragonally-structured Zn3P2 (space group P42/nmc) nanowires, from both experimental and theoretical perspectives. Low-temperature, high-resolution Raman polarization measurements have been performed on single-crystalline nanowires. Different polarization configurations have allowed selective enhancement of A1g, B1g and Eg Raman modes, while B2g modes were identified from complementary unpolarized Raman measurements. Simultaneous deconvolution of all Raman spectra with Lorentzian curves has allowed identification of 33 peaks which have been assigned to 34 (8 A1g + 9 B1g + 3 B2g + 14 Eg) out of the 39 theoretically predicted eigenmodes. The experimental results are in good agreement with the vibrational frequencies that have been computed by first-principles calculations based on density functional theory. Three separate regions were observed in the phonon dispersion diagram: (i) low-frequency region (<210 cm-1) which is dominated by Zn-related vibrations, (ii) intermediate region (210-225 cm-1) which represents a true phonon gap with no observed vibrations, and (iii) high-frequency region (>225 cm-1) which is attributed to primarily P-related vibrations. The analysis of vibrational patterns has shown that non-degenerate modes involve mostly atomic motion along the long crystal axis (c-axis), while degenerate modes correspond primarily to in-plane vibrations, perpendicular to the long c-axis. These results provide a detailed reference for identification of the tetragonal Zn3P2 phase and can be used for building Raman based methodologies for effective defect screening of bulk materials and films, which might contain structural inhomogeneities.

Heterotwin Zn3P2 superlattice nanowires: the role of indium insertion in the superlattice formation mechanism and their optical properties.

Zinc phosphide (Zn3P2) nanowires constitute prospective building blocks for next generation solar cells due to the combination of suitable optoelectronic properties and an abundance of the constituting elements in the Earth's crust. The generation of periodic superstructures along the nanowire axis could provide an additional mechanism to tune their functional properties. Here we present the vapour-liquid-solid growth of zinc phosphide superlattices driven by periodic heterotwins. This uncommon planar defect involves the exchange of Zn by In at the twinning boundary. We find that the zigzag superlattice formation is driven by reduction of the total surface energy of the liquid droplet. The chemical variation across the heterotwin does not affect the homogeneity of the optical properties, as measured by cathodoluminescence. The basic understanding provided here brings new propsects on the use of II-V semiconductors in nanowire technology.

3D Ordering at the Liquid-Solid Polar Interface of Nanowires.

The nature of the liquid-solid interface determines the characteristics of a variety of physical phenomena, including catalysis, electrochemistry, lubrication, and crystal growth. Most of the established models for crystal growth are based on macroscopic thermodynamics, neglecting the atomistic nature of the liquid-solid interface. Here, experimental observations and molecular dynamics simulations are employed to identify the 3D nature of an atomic-scale ordering of liquid Ga in contact with solid GaAs in a nanowire growth configuration. An interplay between the liquid ordering and the formation of a new bilayer is revealed, which, contrary to the established theories, suggests that the preference for a certain polarity and polytypism is influenced by the atomic structure of the interface. The conclusions of this work open new avenues for the understanding of crystal growth, as well as other processes and systems involving a liquid-solid interface.

Genetic Analysis of MECP2 Gene in Iranian Patients with Rett Syndrome.

OBJECTIVES: Rett syndrome is an X linked dominant neurodevelopmental disorder which almost exclusively affects females. The syndrome is usually caused by mutations in MECP2 gene, which is a nuclear protein that selectively binds CpG dinucleotides in the genome. MATERIALS & METHODS: To provide further insights into the distribution of mutations in MECP2 gene, we investigated 24 females with clinical characters of Rett syndrome referred to Alzahra University Hospital in Isfahan, Iran during 2015-2017. We sequenced the entire MECP2 coding region and splice sites for detection of point mutations in this gene. Freely available programs including JALVIEW, SIFT, and PolyPhen were used to find out the damaging effects of unknown mutations. RESULTS: Direct sequencing revealed MECP2 mutations in 13 of the 24 patients. We identified in 13 patients, 10 different mutations in MECP2 gene. Three of these mutations have not been reported elsewhere and are most likely pathogenic. CONCLUSION: Defects in MECP2 gene play an important role in pathogenesis of Rett syndrome. Mutations in MECP2 gene can be found in the majority of Iranian RTT patients. We failed to identify mutations in MECP2 gene in 46% of our patients. For these patients, further molecular analysis might be necessary.

III-V Integration on Si(100): Vertical Nanospades.

III-V integration on Si(100) is a challenge: controlled vertical vapor liquid solid nanowire growth on this platform has not been reported so far. Here we demonstrate an atypical GaAs vertical nanostructure on Si(100), coined nanospade, obtained by a nonconventional droplet catalyst pinning. The Ga droplet is positioned at the tip of an ultrathin Si pillar with a radial oxide envelope. The pinning at the Si/oxide interface allows the engineering of the contact angle beyond the Young-Dupré equation and the growth of vertical nanospades. Nanospades exhibit a virtually defect-free bicrystalline nature. Our growth model explains how a pentagonal twinning event at the initial stages of growth provokes the formation of the nanospade. The optical properties of the nanospades are consistent with the high crystal purity, making these structures viable for use in integration of optoelectronics on the Si(100) platform.

Questioning liquid droplet stability on nanowire tips: from theory to experiment.

Liquid droplets sitting on nanowire (NW) tips constitute the starting point of the vapor-liquid-solid method of NW growth. Shape and volume of the droplet have been linked to a variety of growth phenomena ranging from the modification of growth direction, NW orientation, crystal phase, and even polarity. In this work we focus on numerical and theoretical analysis of the stability of liquid droplets on NW tips, explaining the peculiarity of this condition with respect to the wetting of planar surfaces. We highlight the role of droplet pinning at the tip in engineering the contact angle. Experimental results on the characteristics of In droplets of variable volume sitting on the tips or side facets of InAs NWs are also provided. This work contributes to the fundamental understanding of the nature of droplets contact angle at the tip of NWs and to the improvement of the engineering of such nanostructures.

Optimizing the yield of A-polar GaAs nanowires to achieve defect-free zinc blende structure and enhanced optical functionality.

Compound semiconductors exhibit an intrinsic polarity, as a consequence of the ionicity of their bonds. Nanowires grow mostly along the (111) direction for energetic reasons. Arsenide and phosphide nanowires grow along (111)B, implying a group V termination of the (111) bilayers. Polarity engineering provides an additional pathway to modulate the structural and optical properties of semiconductor nanowires. In this work, we demonstrate for the first time the growth of Ga-assisted GaAs nanowires with (111)A-polarity, with a yield of up to ∼50%. This goal is achieved by employing highly Ga-rich conditions which enable proper engineering of the energies of A and B-polar surfaces. We also show that A-polarity growth suppresses the stacking disorder along the growth axis. This results in improved optical properties, including the formation of AlGaAs quantum dots with two orders or magnitude higher brightness. Overall, this work provides new grounds for the engineering of nanowire growth directions, crystal quality and optical functionality.

Polarization-induced distortion effects on the information rate in single-mode fibers.

In this paper, we examine information theoretical properties of single-mode fibers in the presence of polarization-induced distortion effects. We derive some capacity results and further obtain several nonergodic achievable rates. In this work, however, mostly linear distortions are considered. Since polarization-dependent loss (PDL) is a nonunitary phenomenon, information rate loss caused by PDL is fundamentally inevitable. Interestingly, it is shown that in the presence of channel state information at the transmitter, PDL can increase the capacity in some scenarios. We analytically found also that the highest average capacity improvement from the knowledge of PDL at the transmitter is equal to the mean PDL of the link, and this benefit vanishes at high signal-to-noise ratio. In order to achieve the ergodic capacity, it is established that sending uncorrelated Gaussian signals with equal power via both polarizations is the optimum transmit strategy. As it turns out from the results, perhaps counterintuitively, in the presence of PDL, polarization mode dispersion (PMD) always improves the maximum outage rate; however, the PMD impact on the maximum throughput and the maximum two-layer expected rate is trivial. Finally, an extension to the simple Gaussian noise model of fiber nonlinearity is explored. All theoretical results are illustrated by numerical simulations.

Template-Assisted Scalable Nanowire Networks.

Topological qubits based on Majorana Fermions have the potential to revolutionize the emerging field of quantum computing by making information processing significantly more robust to decoherence. Nanowires are a promising medium for hosting these kinds of qubits, though branched nanowires are needed to perform qubit manipulations. Here we report a gold-free templated growth of III-V nanowires by molecular beam epitaxy using an approach that enables patternable and highly regular branched nanowire arrays on a far greater scale than what has been reported thus far. Our approach relies on the lattice-mismatched growth of InAs on top of defect-free GaAs nanomembranes yielding laterally oriented, low-defect InAs and InGaAs nanowires whose shapes are determined by surface and strain energy minimization. By controlling nanomembrane width and growth time, we demonstrate the formation of compositionally graded nanowires with cross-sections less than 50 nm. Scaling the nanowires below 20 nm leads to the formation of homogeneous InGaAs nanowires, which exhibit phase-coherent, quasi-1D quantum transport as shown by magnetoconductance measurements. These results are an important advance toward scalable topological quantum computing.