Properly Aligned Research Articles

Interface engineering of antimony selenide solar cells: a review on the optimization of energy band alignments

Earth-abundant and environmentally benign antimony selenide (Sb2Se3) has emerged as a promising light-harvesting absorber for thin-film photovoltaic (PV) devices due to its high absorption coefficient, nearly ideal bandgap for PV applications, excellent long-term stability, and intrinsically benign boundaries if properly aligned on the substrate. The record power conversion efficiency of Sb2Se3 solar cells has currently reached 9.2%, however, it is far lower than the champion efficiencies of other chalcogenide thin-film solar cells such as CdTe (22.1%) and Cu(In,Ga)Se2 (23.35%). The inferior device performance of Sb2Se3 thin-film solar cells mainly results from a large open-circuit voltage deficit, which is strongly related to the interface recombination loss. Accordingly, constructing proper band alignments between Sb2Se3 and neighboring charge extraction layers through interface engineering to reduce carrier recombination losses is one of the key strategies to achieving high-efficiency Sb2Se3 solar cells. In this review, the fundamental properties of Sb2Se3 thin films, and the recent progress made in Sb2Se3 solar cells are outlined, with a special emphasis on the optimization of energy band alignments through the applications of electron-transporting layers and hole-transporting layers. Furthermore, the potential research directions to overcome the bottlenecks of Sb2Se3 thin-film solar cell performance are also presented.

Interconnection of Modules of Reconfigurable Modular Robots: A Review

Robots normally perform pre-specified tasks in a predictable environment, like that on shop floor. Normally, assembly-line like operations are performed by robots due to geometrical and programming constraints. Rapidly changing requirments at customer level has greatly influenced the manufacturing technology, due to the risk of obsolescence. Multiple small robots called modules, interconnect with each other its own, to make a great structure are called self reconfigurable modular robots. For few modules, a large number of configurations are possible. As per the level of difficulty of the task, it can take any shape, to complete the work. Each module of the modular robot has its built-in intelligence with separate memory, connection assemblies, detectors and actuators to operate it. Such robots are highly useful in remote operations, especially in hostile environments. For physical docking of the connection plates of the modules, the connection plates should be properly aligned towards each other. This review paper enlightens the capabilities of the modular reconfigurable robots and the techniques explored by some researchers in this field, for proper alignment of the connection plates, for physical docking of modules. Position sensors like hall-effect sensors; and proximity sensors like infrared (IR) detectors and emitters have been used for docking of connection plates of the modules. Controlling and coordinating modules to work together effectively and not collide or otherwise interfere with each other is a bottleneck in this concept. Some work using IR intensity to guide the alignment of the modular robots have already been undertaken. Possibility for the use of MatLab by Mathworks is explored to simulate the alignment for interconnection of Modules of Reconfigurable Modular Robot using data captured by the CCD camera through image recognition.

Bidentate and tridentate metal-ion coordination states within ternary complexes of RB69 DNA polymerase

Two divalent metal ions are required for primer-extension catalyzed by DNA polymerases. One metal ion brings the 3'-hydroxyl of the primer terminus and the α-phosphorus atom of incoming dNTP together for bond formation so that the catalytically relevant conformation of the triphosphate tail of the dNTP is in an α,β,γ-tridentate coordination complex with the second metal ion required for proper substrate alignment. A probable base selectivity mechanism derived from structural studies on Dpo4 suggests that the inability of mispaired dNTPs to form a substrate-aligned, tridentate coordination complex could effectively cause the mispaired dNTPs to be rejected before catalysis. Nevertheless, we found that mispaired dNTPs can actually form a properly aligned tridentate coordination complex. However, complementary dNTPs occasionally form misaligned complexes with mutant RB69 DNA polymerases (RB69pols) that are not in a tridentate coordination state. Here, we report finding a β,γ-bidentate coordination complex that contained the complementary dUpNpp opposite dA in the structure of a ternary complex formed by the wild type RB69pol at 1.88 Å resolution. Our observations suggest that several distinct metal-ion coordination states can exist at the ground state in the polymerase active site and that base selectivity is unlikely to be based on metal-ion coordination alone.

SU‐GG‐T‐542: Accurate Spine SBRT Setup with Properly Aligned MV and CBCT Image Systems

Purpose: Spine SBRT requires high accuracy and precision in treatment setup. It is not well known how to achieve the required patient setup accuracy. We hypothesized that with properly aligned MV EPID and CBCT systems, highly accurate spine setup can be achieved reliably with a three‐stage image‐guided setup process. Method: We used Trilogy with OBI/CBCT imagers for the spine SBRT treatment. At treatment setup, we first took AP and Lat KV images to align the patient with DRR images to bring the planning isocenter near the radiation isocenter. Then we acquired CBCT images, to ensure no excessive patient rotation occurred and to determine the shifts aligned with planning CT using 3D match tools. After the shifts were made, we took AP and Lat MV portal images using EPID with a graticule plate to determine if the patient setup was correct compared to reference DRR. Both CBCT isocenter and the physical graticule were aligned within about 0.5 mm from radiation isocenter. Periodic QA tests were done to monitor the imager alignments. Prior to planning, the planning isocenter was placed strategically so that bony landmarks were aligned with centimeter tick marks in AP and lateral DRR images, where the graticule BB are located in MV images. The CBCT and MV EPID setup were performed with the assumption that abnormalities might occur in each step. Results: A total of 37 consecutive ambulant spine patients were treated in 64 sessions. The discrepancies between MV and CBCT setups were (x, y, z in mm): 0.0±0.5, −0.3±0.6, −0.1±0.4. The maximum deviation was 2 mm in each direction. Conclusion: With properly aligned imaging systems and the three‐stage setup process, we can achieve agreement of within 1 mm along each axis at about 95% confident index between MV and CBCT setups.

Taxonomy of information technology strategy and its impact on the performance of third-party logistics (3PL) in China

This paper develops a taxonomy of information technology strategies used by third-party logistics (3PL) firms in China based on a cluster analysis of survey data from 105 of these 3PL firms. The information technology strategies have been classified into three major groups: supportive, technological, and aligned. The paper also investigates the effect of information technology strategies on information technology advantage, competitive advantage, and financial performance. The results of the study indicate that efforts to improve information technology systems can only be effective if the information technology improvements are properly aligned with a company's overall strategy. It is found that companies that attempt to improve their information technology systems without the proper alignment of information technology with the company's overall strategy can achieve information technology advantages relative to their competitors, but not competitive advantages or improved financial performance. This study is the first attempt to develop an information technology strategy taxonomy for 3PL companies in China. It provides valuable guidance and insights for managers in the development of information technology strategies in 3PL companies.

Sensing Properly Aligned Chromosomes

Cell division is all about precise separation of sister chromatids to the daughter cells. In fact, cells have a fail-safe mechanism known as the mitotic checkpoint through which the cell division process is only allowed to proceed if every chromosome is attached to the microtubules of the mitotic spindle. Malfunction of this process is thought to contribute to chromosome instability in cancer cells. Some controversy has surrounded the question of whether the checkpoint mechanism actually senses attachment to microtubules per se or the tension that results from it. Mao et al. provide new experiments that support the former model. BubR1 is a protein kinase that is active at unattached kinetichores and contributes to the signal that stops progression of anaphase. The centromere-associated kinesin family member CENP-E binds to and stimulates BubR1, and the motor domain of CENP-E binds microtubules. Mao et al. show in Xenopus egg extracts or transfected mammalian cells that a form of CENP-E that cannot bind microtubules keeps BubR1 in an active state and prevents completion of mitosis, even if chromosomes are all attached to the spindle. In vitro, the authors could reconstitute the checkpoint signal. They mixed microtubules formed from purified tubulin with recombinant BubR1 and CENP-E and showed that after interaction with microtubules, CENP-E became an inhibitor of BubR1 activity. Thus, the authors contend that CENP-E is the critical signal-transducing sensor that inactivates the checkpoint signal once chromosomes are properly attached to the spindle. Y. Mao, A. Desai, D. W. Cleveland, Microtubule capture by CENP-E silences BubR1-dependent mitotic checkpoint signaling. J. Cell Biol. 170 , 873-880 (2005). [Abstract] [Full Text]

Analysis of esthetic smiles by using computer vision techniques

Properly aligned teeth and a beautiful smile are the twin goals of orthodontic treatment. Unfortunately, a change in the smile arc is sometimes an unintended consequence of proper alignment. We used 3-dimensional dental models and visualization techniques, including curve-fitting and image-processing algorithms, to analyze smile arcs with respect to different parameters. The results show that smile consonance depends greatly on the conversational distance and the angle of elevation between the viewer and the smile.

A γ Gly-268 to Glu Substitution Is Responsible for Impaired Fibrin Assembly in a Homozygous Dysfibrinogen Kurashiki I

A new type of gamma Gly-268 (GGA) to Glu (GAA) substitution has been identified in a homozygous dysfibrinogen by analyses of the affected polypeptide and its encoding gene derived from a 58 year-old man manifesting no major bleeding or thrombosis. The functional abnormality was characterized by impaired fibrin assembly most likely due to failure to construct properly aligned double-stranded fibrin protofibrils. This presumption was deduced from the following findings: (1) Factor XIIIa-catalyzed cross-linking of the fibrin gamma-chains progressed in a normal fashion, indicating that the contact between the central E domain of one fibrin monomer and the D domain of another took place normally; (2) Nevertheless, factor XIIIa-catalyzed cross-linking of the fibrinogen gamma-chains was obviously delayed, suggesting that longitudinal association of D domains of different fibrin monomers, ie, D:D association was perturbed; (3) Plasminogen activation catalyzed by tissue-type plasminogen activator was not as efficiently facilitated by polymerizing fibrin monomer derived from the patient as by the normal counterpart. Therefore, gamma Gly-268 would not be involved in the 'a' site residing in the D domain, which functions as a complementary binding site with the thrombin-activated 'A' site in the central E domain, but would be rather involved in the D:D self association sites recently proposed for human fibrinogen. Thus, the gamma Glu-268 substitution newly identified in this homozygous dysfibrinogen seems to impair proper alignment of adjacent D domains of neighboring fibrin molecules in the double-stranded fibrin protofibril, resulting in delayed fibrin gel formation.

COLLIMATION OF FAST WIDE-FIELD TELESCOPES

ABSTRACT In this paper, I present a simple technique for collimating the secondary mirror of fast focal ratio wide-field Cassegrain telescopes. This technique minimizes both coma and astigmatism across the field. Because astigmatism is nearly zero on-axis even in a misaligned system, it is necessary to make measurements off-axis. This technique is useful on telescopes corrected for off-axis coma such as Ritchey-Cretien designs and classical Cassegrains with refractive correctors. Proper alignment for astigmatism is especially important in the latter type of telescope where there is no astigmatism across the field in a properly aligned system. The tools required for collimation are a camera that can examine images at several locations at the edge of the field and a secondary mirror that can be controlled in five axes. Also presented are analytic expressions for the amount of field-dependent astigmatism due to miscollimation. The technique is robust enough to collimate telescopes with fixed astigmatism in the telescope primary.

Rheological properties of confined thin films.

Shearing of monolayer and bilayer monatomic films confined between planar solid surfaces (walls) is simulated by a Monte Carlo technique in the isostress-isostrain ensemble, where temperature, number of film atoms, and applied normal stress are state variables. The walls consist of individual atoms that are identical with the film atoms and are fixed in the fcc (face centered cubic) (100) configuration. The lattice constant l of the walls is varied so that the walls are either commensurate with the (solid) film at fixed nominal lattice constant ${\mathit{l}}_{\mathit{f}}$ (i.e., l/${\mathit{l}}_{\mathit{f}}$=1) or homogeneously compressed (l/${\mathit{l}}_{\mathit{f}}$1) or stretched (l/${\mathit{l}}_{\mathit{f}}$>1). Such rheological properties as shear stress ${\mathit{T}}_{\mathit{z}\mathit{x}}$ and modulus are correlated with molecular structure of the layers, as reflected in translational and orientational correlation functions. If the walls are properly aligned in transverse directions, then the layers exhibit a high degree of fcc order. As such ordered films are subjected to a shear strain (by reversibly moving the walls out of alignment), they respond initially as an elastic solid: at small strains, ${\mathit{T}}_{\mathit{z}\mathit{x}}$ depends linearly on the strain. As the shear strain increases, the response becomes highly nonlinear: ${\mathit{T}}_{\mathit{z}\mathit{x}}$ rises to a maximum (yield point) and then decays monotonically to zero, where the maximum misalignment of the walls occurs. The correlation functions indicate that the films are not necessarily solid, even when the walls are in proper alignment. The results suggest that the principal mechanism by which disordered nonsolid films are able to resist shearing is ``pinning'': the film atoms are trapped in effective cages formed by their near neighbors and the mutual attraction of the walls for the caged atoms pins them together.

Technique to assure proper intraoral wound edge alignment

During the performance of an intraoral osteotomy, the incision in the posterior mandibular mucogingival fold is stretched a great deal due to the retractors used to provide access to the ramus. At the conclusion of the procedure, most surgeons simply close the wound edges as they line up. If the wound is not properly aligned for closure, malpositioning occurs and the resulting scar can form a band of tissue which can be a problem to the patient either because of irritation or creation of a food trap