Single-wavelength bidirectional 4-core MCF self-homodyne coherent link.

In this paper, we propose and demonstrate a single-wavelength bidirectional self-homodyne coherent (SHC) link over a 125 µm cladding diameter based multicore fiber (MCF). The 4-core MCF based link efficiently uses two cores for each direction of propagation. In either direction, one of the cores carries a dual-polarized 40 Gbaud 16-QAM signal, and the second core carries a 40 Gbaud 16-QAM signal in one of the polarizations with the carrier multiplexed in its orthogonal polarization. Thus, a 480 Gbps data transmission rate is achieved in either direction of propagation over the 12.8 km long 4-core MCF. The SHC link operates at the same wavelength for each of the directions and eliminates the need for reconfigurable transceivers. A low-cost DFB laser (linewidth = 1 MHz) is used to demonstrate the bidirectional link, and the bit error rates (BERs) of the received signals are <5.5×10-4. With higher baud rates, this approach can meet the capacity requirements of future short-reach data center interconnects (DCIs).

Adaptive electro-optic equalization in low-power coherent-lite interconnects.

In this paper, we propose an adaptive electro-optic equalizer for short-reach interconnects employing coherent modulation and detection. The equalizer consists of two main components: an optical equalizer filter and an electronic controller. The equalizer filter compensates for the linear dispersion occurring in the channel, while the electronic controller adaptively determines the weight coefficients of the equalizer. To achieve adaptive adjustment, we have introduced a random search algorithm. Extensive simulations have been conducted to evaluate the performance of the equalizer in a 120 Gbaud homodyne coherent link, and the results show great promise. The proposed equalizer has the potential to greatly improve the overall power efficiencies of receivers in short-reach coherent-lite interconnects.

Demonstration of a low-power, local-oscillator-less, and DSP-free coherent receiver for data center interconnects.

Performance limitations of currently employed four-level pulse amplitude modulation links and high power consumption of digital signal processing (DSP)-based coherent links for further increase in capacity create an urgent demand for low-power coherent solutions for short-reach data center interconnects. We propose a low-power coherent receiver with analog domain processing for a self-homodyne link. To validate the proposed scheme, a 10 GBd polarization multiplexed carrier-based self-homodyne quadrature phase-shift keying system with a constant modulus algorithm-based equalizer chip is experimentally demonstrated. Also, energy consumption per bit estimates show that the proposed approach results in significant power reduction in comparison with conventional DSP-based solutions.

Coupling sensitivity and radiation pattern of a vertical grating coupler.

Analytical expressions of electric field radiation pattern, coupling sensitivity, and scattering parameters of vertical grating couplers have been derived in this paper. Excellent agreement has been found between these expressions, finite element method (FEM) simulations, and experimental results. The results give an insight on how to design vertical grating couplers and reduce the number of iterations while designing and efficiently aligning the fiber over the chip without carrying out time-consuming electromagnetic simulations for the couplers.

Topological characterization and early detection of bifurcations and chaos in complex systems using persistent homology.

Early detection of bifurcations and chaos and understanding their topological characteristics are essential for safe and reliable operation of various electrical, chemical, physical, and industrial processes. However, the presence of non-linearity and high-dimensionality in system behavior makes this analysis a challenging task. The existing methods for dynamical system analysis provide useful tools for anomaly detection (e.g., Bendixson-Dulac and Poincare-Bendixson criteria can detect the presence of limit cycles); however, they do not provide a detailed topological understanding about system evolution during bifurcations and chaos, such as the changes in the number of subcycles and their positions, lifetimes, and sizes. This paper addresses this research gap by using topological data analysis as a tool to study system evolution and develop a mathematical framework for detecting the topological changes in the underlying system using persistent homology. Using the proposed technique, topological features (e.g., number of relevant k-dimensional holes, etc.) are extracted from nonlinear time series data which are useful for deeper analysis of the system behavior and early detection of bifurcations and chaos. When applied to a Logistic map, a Duffing oscillator, and a real life Op-amp based Jerk circuit, these features are shown to accurately characterize the system dynamics and detect the onset of chaos.

To Study the Clinical Profile and Management of Cellulitis of Lower Limb in Northern India.

Cellulitis is a bacterial infection of the dermis and subcutaneous tissues occupying a large proportion of hospital beds. This study was conducted for analysis of patients with cellulitis according to their demographics and clinical presentation and to examine their comorbidities, complications, and its management. This observational cross-sectional study was conducted in the Department of Surgery at Santosh Medical College and Hospitals involving a total of 60 cases having cellulitis and other soft tissue infections of lower limb. Analysis of their demographic profile, management, and complications was done. Cellulitis is seen commonly in males, 46 (76.6%). The mean age of patients affected by cellulitis in the study was 36.4 ± 1.23 years. The most common site affected is leg involving more people in field jobs. The most common risk factor was trauma in 46.6%, and other factors were diabetes mellitus and smoking, while abscess formation was the most common complication observed in 36.6% of cases. A total of 56.6% cases were managed conservatively, while 43.3% cases required surgical intervention. Mean hospital stay in this study was 5.02 ± 0.23 days. It was concluded that cellulitis is subcutaneous, spreading bacterial infection is more common in males, and its incidence is highest in working age group population. Lower limb is commonly involved. Trauma, smoking, and diabetes are significant risk factors for development of cellulitis. Abscess is the most common complication. About 50% patients with cellulitis can be managed conservatively and the rest require surgical intervention.

BaAu(x)Zn(13-x): electron-poor cubic NaZn13-type intermetallic and its ordered tetragonal variant.

Cubic NaZn(13)-type (Fm-3c, Z = 8) BaAu(x)Zn(13-x) compounds in the regions 1 ≤ x ≤ 5.4 (a = 12.418(1)-12.590(1) Å) and 6.4 ≤ x ≤ 8 (a = 12.630(1)-12.660(1) Å) plus an ordered tetragonal variant near x = 6 (P4/nbm; a = 8.8945(4) Å, c = 12.646(1) Å; Z = 4) have been synthesized and characterized by means of X-ray diffraction. Although the cubic structure contains Zn-centered, mixed (Zn, Au) icosahedra connected in alternate orientations via mixed tetrahedral stars (TS), the icosahedron vertices are ordered in the tetragonal structure. Both the inner and the outer tetrahedra in the TS in the cubic phase consist of mixed Au and Zn atoms, whereas the tetragonal phase features three different coloring schemes: inner Zn and outer Au tetrahedra, vice versa, or mixed Au and Zn sites on both inner and outer tetrahedra. Barium atoms center 24-atom snub cuboctahedra. Ordering of Au and Zn in the tetragonal phase achieves the largest number of heteroatomic Au-Zn contacts and yields relatively larger Hamilton populations (-ICOHPs) compared with homoatomic counterparts according to LMTO-based electronic structure calculations and analysis. Larger overlap populations are also observed for inter- versus intraicosahedral interactions. The densities-of-states data suggest the phase is metallic with highly dispersed Au d bands and nearly free-electron-like s and p bands for both Au and Zn.

Digital broadband linearization technique and its application to photonic time-stretch analog-to-digital converter.

Suppression of distortion induced by nonlinearity in a dynamical system (such as an analog optical link) is very challenging, particularly for a wide-bandwidth signal. Conventional compensation techniques are computationally intensive, significantly limiting their realization in real-time applications. Here, we propose and demonstrate an efficient digital postprocessing technique to suppress distortions added to a wideband signal by a nonlinear system with memory effect. Experimentally, digital broadband linearization of the photonic time-stretch analog-to-digital converter (TSADC) is demonstrated. In case of TSADC, a dynamic range improvement of >15 dB compared to conventional memory-less correction method is achieved.

Synthesis, structure, and bonding of BaTl4. Size effects on encapsulation of cations in electron-poor metal networks.

The synthesis, structure, and bonding of BaTl(4) are described [C2/m, Z = 4, a = 12.408(3), b = 5.351(1), c = 10.383(2) Å, ß = 116.00(3)°]. Pairs of edge-sharing Tl pentagons are condensed to generate a network of pentagonal biprisms along b that encapsulate Ba atoms. Alternating levels of prisms along c afford six more bifunctional Tl atoms about the waists of the biprisms, giving Ba a coordination number of 16. Each Tl atom is bonded to five to seven other Tl atoms and to three to five Ba atoms. There is also strong evidence that Hg substitutes preferentially in the shared edges of the Tl biprisms in BaHg(0.80)Tl(3.20) to generate more strongly bound Hg(2) dimers. Cations that are too small relative to the dimensions of the surrounding polyanionic network make this BaTl(4) structure (and for SrIn(4) and perhaps EuIn(4) as well) one stable alternative to tetragonal BaAl(4)-type structures in which cations are bound in larger hexagon-faced nets, as for BaIn(4) and SrGa(4). Characteristic condensation and augmentation of cation-centered prismatic units is common among many relatively cation- and electron-poor, polar derivatives of Zintl phases gain stability. At the other extreme, the large family of Frank-Kasper phases in which the elements exhibit larger numbers of bonded neighbors are sometimes referred to as orbitally rich.

Protein-assisted scalable mechanochemical exfoliation of few-layer biocompatible graphene nanosheets.

A facile method to produce few-layer graphene (FLG) nanosheets is developed using protein-assisted mechanical exfoliation. The predominant shear forces that are generated in a planetary ball mill facilitate the exfoliation of graphene layers from graphite flakes. The process employs a commonly known protein, bovine serum albumin (BSA), which not only acts as an effective exfoliation agent but also provides stability by preventing restacking of the graphene layers. The latter is demonstrated by the excellent long-term dispersibility of exfoliated graphene in an aqueous BSA solution, which exemplifies a common biological medium. The development of such potentially scalable and toxin-free methods is critical for producing cost-effective biocompatible graphene, enabling numerous possible biomedical and biological applications. A methodical study was performed to identify the effect of time and varying concentrations of BSA towards graphene exfoliation. The fabricated product has been characterized using Raman spectroscopy, powder X-ray diffraction, transmission electron microscopy and scanning electron microscopy. The BSA-FLG dispersion was then placed in media containing Astrocyte cells to check for cytotoxicity. It was found that lower concentrations of BSA-FLG dispersion had only minute cytotoxic effects on the Astrocyte cells.

Contrasts in structural and bonding representations among polar intermetallic compounds. Strongly differentiated Hamilton populations for three related condensed cluster halides of the rare-earth elements.

The crystal and electronic structures of three related R(3)TnX(3) phases (R = rare-earth metal, Tn = transition metal, X = Cl, I) containing extended mixed-metal chains are compared and contrasted: (1) Pr(3)RuI(3) (P2(1)/m), (2) Gd(3)MnI(3) (P2(1)/m), and (3) Pr(3)RuCl(3) (Pnma). The structures all feature double chains built of pairs of condensed R(6)(Tn) octahedral chains encased by halogen atoms. Pr(3)RuI(3) (1) lacks significant Ru-Ru bonding, evidently because of packing restrictions imposed by the large closed-shell size of iodine. However, the vertex Pr2 atoms on the chain exhibit a marked electronic differentiation. These are strongly bound to the central Ru (and to four I), but very little to four neighboring Pr in the cluster according to bond populations, in contrast to Pr2-Pr "bond" distances that are very comparable to those elsewhere. In Gd(3)MnI(3) (2), the smaller metal atoms allow substantial distortions and Mn-Mn bonding. Pr(3)RuCl(3) (3), in contrast to the iodide (1), can be described in terms of a more tightly bound superstructure of (2) in which both substantial Ru-Ru bonding and an increased number of Pr-Cl contacts in very similar mixed-metal chains are favored by the smaller closed-shell contacts of chlorine. Local Spin Density Approximation (LSDA) Linearized Muffin-Tin Orbital (LMTO)-ASA calculations and Crystal Orbital Hamilton Population (COHP) analyses show that the customary structural descriptions in terms of condensed, Tn-stuffed, R-R bonded polyhedral frameworks are poor representations of the bonding in all. Hamilton bond populations (-ICOHP) for the polar mixed-metal R-Tn and the somewhat smaller R-X interactions account for 75-90% of the total populations in each of these phases, together with smaller contributions and variations for R-R and Tn-Tn interactions. The strength of such R-Tn contributions in polar intermetallics was first established or anticipated by Brewer. The rare-earth-metal atoms are significantly oxidized in these compounds.

BaHg2Tl2. An unusual polar intermetallic phase with strong differentiation between the neighboring elements mercury and thallium.

High yields of the novel BaHg(2)Tl(2) are achieved from reactions of the appropriate cast alloys at approximately 400 degrees C. (Isotypic SrHg(2)Tl(2) also exists.) The tetragonal barium structure (P4(2)/mnm, a = 10.606 A, c = 5.159 A) was refined from both single-crystal X-ray and neutron powder diffraction data in order to ensure the atom site assignments although distances and calculated atom site population also support the results. The Hg and Tl network atoms are distinctive in their functions and bonding. Parallel chains of Hg hexagons and of Tl tetrahedra along c are constructed from polyhedra that share opposed like edges, and these are in turn interconnected by Hg-Tl bonds. Overall, the number of Tl-Tl bonds per cell exceeds the Hg-Hg type by 20:12, but these are approximately 1:2 each in bonding according to their average -ICOHP values (related to overlap populations). Barium is bound within a close 15-atom polyhedron, 12 atoms of which are the more electronegative Hg. LMTO-ASA calculations show that scalar relativistic effects are particularly important for Hg 5d-6s mixing in Hg-Hg and Hg-Tl bonding, whereas relatively separate Tl 6s and 6p states are more important in Tl-Tl interactions. The 6p states of Hg and Tl and 5d of Ba define a dominant conduction band around E(F), and the phase is metallic and Pauli-like paramagnetic. The thallium characteristics here are close to those in numerous alkali-metal-Tl cluster systems. Other active metal-mercury phases that have been studied theoretically are all distinctly electron-richer and more reduced, and without appreciable net 5d, 6s contributions to Hg-Hg bonding.

R(5)Pn(3)-type phases of the heavier trivalent rare-earth-metal pnictides (Pn = Sb, Bi): new phase transitions for Er(5)Sb(3) and Tm(5)Sb(3).

The syntheses and distributions of binary R(5)Pn(3) phases among the hexagonal Mn(5)Si(3) (M), and the very similar orthorhombic beta-Yb(5)Sb(3) (Y) and Y(5)Bi(3) (YB) structure types have been studied for R = Y, Gd-Lu and Pn = Sb, Bi. Literature reports of M and YB-type structure distributions among R(5)Pn(3) phases, R = Y, Gd-Ho, are generally confirmed. The reported M-type Er(5)Sb(3) could not be reproduced. Alternate stabilization of Y-type structures by interstitials H or F has been disproved for these nominally trivalent metal pnictides. Single crystal structures are reported for (a) the low temperature YB form of Er(5)Sb(3) (Pnma, a = 7.9646(9) A, b = 9.176(1) A, c = 11.662(1) A), (b) the YB- and high temperature Y-types of Tm(5)Sb(3) (both Pnma, a = 7.9262(5), 11.6034(5) A, b = 9.1375(6), 9.1077(4) A, c = 11.6013(7), 7.9841(4) A, respectively), and (c) the YB structure of Lu(5)Sb(3), a = 7.8847(4) A, b = 9.0770(5) A, c = 11.5055(6) A. Reversible, temperature-driven phase transitions (beta-Yb(5)Sb(3) left arrow over right arrow Y(5)Bi(3) types) for the former Er(5)Sb(3) and Tm(5)Sb(3) around 1100 degrees C and the means of quenching the high temperature Y form, have been esstablished. According to their magnetic susceptibilities, YB-types of Er(5)Sb(3) and Tm(5)Sb(3) contain trivalent cations. Tight-binding linear muffin-tin-orbital method within the atomic sphere approximation (TB-LMTO-ASA) calculations for the two structures of Tm(5)Sb(3) reveal generally similar electronic structures but with subtle Tm-Tm differences supporting their relative stabilities. The ambient temperature YB-Tm(5)Sb(3) shows a deep pseudogap at E(F), approaching that of a closed shell electronic state. Short R-R bonds (3.25-3.29 A) contribute markedly to the structural stabilities of both types. The Y-type structure of Tm(5)Sb(3) shows both close structural parallels to, and bonding contrasts with, the nominally isotypic, stuffed Ca(5)Bi(3)D and its analogues. Some contradictions in the literature are discussed.

Comparative Analysis of Hemodynamic Changes and Shoulder Tip Pain Under Standard Pressure Versus Low-pressure Pneumoperitoneum in Laparoscopic Cholecystectomy.

BACKGROUND: Laparoscopic cholecystectomy is the gold standard procedure for cholelithiasis. Pneumoperitoneum is created using carbon dioxide (CO2) which is usually maintained at a range of 12-14 mm Hg. An emerging trend has been the use of low-pressure pneumoperitoneum in the range of 7-10 mm Hg in an attempt to lower the impact of pneumoperitoneum on the human physiology while providing adequate working space. Our study proposes to compare the effects of low-pressure pneumoperitoneum with the use of standard pressure of pneumoperitoneum. AIMS AND OBJECTIVE: To compare and analyze various factors like blood pressure, heart rate, end-tidal CO2 and postoperative shoulder tip pain in cases undergoing laparoscopic cholecystectomy using standard pressure versus low pressure. MATERIALS AND METHODS: This is a prospective randomized study carried out at Santosh Medical College and Hospitals, Ghaziabad from September 2017 to December 2018. This study included 60 patients of cholelithiasis which were divided into two groups of 30 patients each. Group I was offered laparoscopic cholecystectomy under standard pressure pneumoperitoneum and group II underwent laparoscopic cholecystectomy using low-pressure pneumoperitoneum. Patients in each group were evaluated for various intraoperative physiological changes and postoperative shoulder tip pain. OBSERVATIONS AND RESULTS: Cholelithiasis is commonly seen in middle-aged females. There is no significant difference in duration of surgery between the two groups. However, various factors like systolic blood pressure, heart rate, end-tidal CO2 were significantly better in the low-pressure group. Postoperative shoulder tip pain (measured by VAS scoring system) was significantly less in the low-pressure group during the first 24 hours. CONCLUSION: Laparoscopic cholecystectomy under low-pressure pneumoperitoneum causes minimal physiological changes and less postoperative shoulder tip pain. HOW TO CITE THIS ARTICLE: Goel A, Gupta S, et al. Comparative Analysis of Hemodynamic Changes and Shoulder Tip Pain Under Standard Pressure Versus Low-pressure Pneumoperitoneum in Laparoscopic Cholecystectomy. Euroasian J Hepatogastroenterol 2019;9(1): 5-8.

Inkjet Printing of Magnetic Particles Toward Anisotropic Magnetic Properties.

Unique properties of one-dimensional assemblies of particles have attracted great attention during the past decades, particularly with respect to the potential for anisotropic magnetism. Patterned films can be created using inkjet printing; however, drying of particle-laden colloidal droplets on solid surfaces is usually accompanied by the well-known coffee-ring effect, deteriorating both the uniformity and resolution of the printed configurations. This study examines the effect of externally applied magnetic field on particle deposition patterns. Ferromagnetic Gd5Si4 particles were formulated in terpineol oil and directly deposited via magnetic field-assisted inkjet printing on a photopaper to generate patterned films with suppressed coffee-ring effect. The particle deposition morphology is determined by both solvent imbibition and particle-magnetic field interactions. Three characteristic times are considered, namely, the critical time for solvent imbibition into the substrate (tim), the time it takes for particles to form chains in the presence of the magnetic field (tch), and the time in which the particles reach the substrate in the direction normal to the substrate (tpz). The characteristic time ratios (tpz/tim) and (tpz/tch) determine the final deposition morphology in the presence of magnetic field. The ability to control particle deposition and assembly, thus tuning the magnetic anisotropic properties of nanostructured materials is a promising approach for many engineering applications.

Recycling of additively printed rare-earth bonded magnets.

In this work, we describe an efficient and environmentally benign method of recycling of additive printed Nd-Fe-B polymer bonded magnets. Rapid pulverization of bonded magnets into composite powder containing Nd-Fe-B particles and polymer binder was achieved by milling at cryogenic temperatures. The recycled bonded magnets fabricated by warm compaction of ground cryomilled coarse composite powders and nylon particles showed improved magnetic properties and density. Remanent magnetization and saturation magnetization increased by 4% and 6.5% respectively, due to enhanced density while coercivity and energy product were retained from the original additive printed bonded magnets. This study presents a facile method that enables the direct reuse of end-of-life bonded magnets for remaking new bonded magnets. In addition to magnetic properties, mechanical properties comparable to commercial products have been achieved. This research advances efforts to ensure sustainability in critical materials by forming close loop supply chain.

POSE: Prediction-Based Opportunistic Sensing for Energy Efficiency in Sensor Networks Using Distributed Supervisors.

This paper presents a distributed supervisory control algorithm that enables opportunistic sensing for energy-efficient target tracking in a sensor network. The algorithm called Prediction-based Opportunistic Sensing (POSE), is a distributed node-level energy management approach for minimizing energy usage. Distributed sensor nodes in the POSE network self-adapt to target trajectories by enabling high power consuming devices when they predict that a target is arriving in their coverage area, while enabling low power consuming devices when the target is absent. Each node has a Probabilistic Finite State Automaton which acts as a supervisor to dynamically control its various sensing and communication devices based on target's predicted position. The POSE algorithm is validated by extensive Monte Carlo simulations and compared with random scheduling schemes. The results show that the POSE algorithm provides significant energy savings while also improving track estimation via fusion-driven state initialization.

Wavelet-based information filtering for fault diagnosis of electric drive systems in electric ships.

Electric machines and drives have enjoyed extensive applications in the field of electric vehicles (e.g., electric ships, boats, cars, and underwater vessels) due to their ease of scalability and wide range of operating conditions. This stems from their ability to generate the desired torque and power levels for propulsion under various external load conditions. However, as with the most electrical systems, the electric drives are prone to component failures that can degrade their performance, reduce the efficiency, and require expensive maintenance. Therefore, for safe and reliable operation of electric vehicles, there is a need for automated early diagnostics of critical failures such as broken rotor bars and electrical phase failures. In this regard, this paper presents a fault diagnosis methodology for electric drives in electric ships. This methodology utilizes the two-dimensional, i.e. scale-shift, wavelet transform of the sensor data to filter optimal information-rich regions which can enhance the diagnosis accuracy as well as reduce the computational complexity of the classifier. The methodology was tested on sensor data generated from an experimentally validated simulation model of electric drives under various cruising speed conditions. The results in comparison with other existing techniques show a high correct classification rate with low false alarm and miss detection rates.

Luminescence properties of mechanochemically synthesized lanthanide containing MIL-78 MOFs.

Three metal-organic framework (MOF) compounds, Ln0.5Gd0.5{C6H3(COO)3}; Ln = Eu, Tb, and Dy with a MIL-78 structure, have been synthesized by a solvent-free mechanochemical method from stoichiometric mixtures of benzene 1,3,5-tricarboxylic acid, C6H3(COOH)3, also known as trimesic acid, and the respective lanthanide carbonates, Ln2(CO3)3·xH2O, Ln = Eu, Gd, Tb and Dy. MIL-78 (Ln0.5Gd0.5) shows the characteristic red, green, and yellow luminescence of Eu3+, Tb3+, and Dy3+, respectively. Efficient intramolecular energy transfer from the ligand triplet state to the excited states of Ln3+ ions can be observed. The lifetimes and quantum yields of these compounds are studied and discussed in detail. Among the three compounds, the Tb3+ containing compound shows the longest lifetime and highest quantum yield due to a smaller contribution from non-radiative decay pathways and better matching of the lowest triplet energy level of the benzenetricarboxylate ligand and the resonance level of Tb3+.

Innovative Economical Surgical Suture Board.

The aim of this study is to develop an economical suture board for practising suturing skills and techniques. Suture boards were made by using local electric boards, small leather patch, four suction buttons, six screws and a hook. These suture boards are multipurpose boards which are economical and available all the time in department for practicing. This board can also be placed in endotrainer for laparoscopic suturing skills. This economical suture board is cheap, easily available and helps in practicing various suturing and knot tying techniques.