End-to-end Research Articles

A Binuclear Azido-Bridged Manganese Complex: Synthesis, Crystal Structure and Magnetic Properties

The azido-bridged binuclear manganese complex [{Mn(0.5H2O)(0.5N3)(tptz)(NO3)}2(μ1,3-N3)] [tptz=2,4,6-tris(2-pyridyl)-1,3,5-triazine] has been synthesised and structurally characterised. Two [Mn(0.5H2O)(0.5N3)(tptz)(NO3)] units are bridged by the end-to-end (EE) azide ligand. The Mn atoms are seven coordinated, with the five equatorial positions occupied by three N atoms of the tptz ligands and two O atoms of the nitrate ion and the two axial positions are coordinated by the N atom of the bridge azide ligand and the N atom of the disordered terminal azide ligand or the O atom of a disordered solvent water molecule, respectively. Magnetic susceptibility investigation shows antiferromagnetic coupling between the adjacent Mn(II) ions bridged by the azide ligands.

Echocardiographic Follow up After Surgical Correction of Aortic Coarctation During The First Year of Life

Abstract Coarctation of the aorta (AoCo) accounts for 6–10% of congenital heart diseases in infants. We analysed echocardiographic findings of patients operated on for AoCo in the University Hospital for Children in Riga during the first year of life to evaluate the long-term findings. Fifty-nine children underwent surgical correction of AoCo at the age of 55 ± 61 days. The methods of surgical correction were anastomosis end-to-end (ETE) in 29% (n = 17), subclavian flap aortoplasty (SFA) in 64% (n = 38) and extended anastomosis end-to-end (EETE) in 7% (n = 4). Recoarctation developed in 15 patients (25%) with no difference between surgical techniques (P > 0.05). The recoarcation patients had left ventricle hypertrophy (left ventricle mass index (LVMi) 76 ± 19 g/m2.7) normalising after angioplasty (LVMi 42 ± 7 g/m2.7). Patients with recoarctation had a decreased pulsed wave (PW) Doppler systolic/diastolic ratio in abdominal aorta 2.3 ± 0.4 versus patientswithout recoarctation 5.3 ± 1.2 and the control group 6.3 ± 1.4 (P < 0.05). A high incidence of recoarctation exists in patients operated on for AoCo as small infants. Life-long surveillance is required to monitor and to intervene in a timely way. Supplementation of the echocardiographic protocol with an evaluation of PW Doppler flow pattern in abdominal aorta can provide additional information about the presence of obstruction.

End-to-end and side-by-side assemblies of gold nanorods induced by dithiol poly(ethylene glycol)

The assemblies of gold nanorods (Au NRs) exhibit unique properties distinct from the isolated Au NR. We report an effective and simple method for the end-to-end (E-E) and side-by-side (S-S) assemblies of Au NRs with a molecularly defined nanogap (1–2 nm) only in the presence of dithiol poly(ethylene glycol) (HS-PEG-SH). The assembled methods need neither the pH value adjustments nor the addition of other organic solvent. With increasing amount of dithiol molecules, assembled modes of Au NRs experience an interesting procedure, changing from E-E to S-S orientation. The experimental results indicate that when the concentration of HS-PEG-SH is less than 0.25 μM, electrostatic repulsion of positive-charged CTA+ is stronger than the affinity of the Au-S binding, resulting in the E-E oriented assembly. Otherwise, the S-S oriented mode is predominated. The current assembled method will be potentially useful for the optoelectronics and biomedical engineering.

Telephone Call Duration Measurement Reference System

The problems about telecommunication networks call duration measurement equipment validation and verification procedures are discussed in the paper. Because the maximum permissible error of network’s call duration measurement system comprises many error terms that depend on telecommunication network structure, technology, call processing, etc., the “end–to-end” testing procedure have to be used. Therefore special reference system providing traceability of time measurements in telecommunications and measuring the duration of the test calls independent of network’s equipment, utilizing “end-to-end” measurement principle, was developed. The structure and operation principles of the reference system are presented in details in the paper. Evaluated call duration measurement expanded uncertainty and systematic correction of the developed reference system is less than 0.1 s. DOI: http://dx.doi.org/10.5755/j01.eee.20.6.3773

Early sensory protection in reverse end-to-side neurorrhaphy to improve the functional recovery of chronically denervated muscle in rat: a pilot study.

Early innervation by sensory nerves has been proposed to prevent atrophy of chronically denervated muscle, but conventional end-to-end (ETE) neurorrhaphy has been demonstrated to have adverse effects on muscle contractile function. The aim of the present study was to investigate the potential for modified sensory nerve protection in reverse end-to-side (ETS) neurorrhaphy as a way of improving the functional recovery of denervated muscle. Four groups of rats underwent surgical denervation of the tibial nerve projecting to the right hindlimbs (Group 1, unprotected controls; Group 2, positive control [immediate repair without delayed denervation]; Group 3, ETS protected; and Group 4, ETE protected). The proximal and distal stumps of the tibial nerve were ligated in all animals except for those in the immediate-repair group. Other animals underwent denervation without sural nerve protection, or with ETE or ETS neurorrhaphy. The ETE- and ETS-protected and unprotected groups underwent an additional surgery in which the trimmed proximal and distal tibial nerve stumps were sutured together. After 3 months of recovery, the tibial function index was determined, and electrophysiological, histological, and morphometric parameters were assessed. Significant muscle atrophy was observed in the unprotected group, while a well-preserved ultrastructure was observed for the gastrocnemius muscle in the ETE- and ETS-protected groups. Enhanced recovery in the ETS-protected group was indicated by the tibial function index, motor nerve conduction velocity, muscle contractile force tests, and the histological results. In contrast, early sensory nerve protection in ETE neurorrhaphy impaired the recovery of the regenerated axons and diminished the contractile force of the denervated muscle. Early sensory protection in reverse ETS neurorrhaphy is an effective method for improving the functional recovery of chronically denervated muscle following peripheral nerve injury in rats.

Hierarchical Communication Network Architectures for Offshore Wind Power Farms

Nowadays, large-scale wind power farms (WPFs) bring new challenges for both electric systems and communication networks. Communication networks are an essential part of WPFs because they provide real-time control and monitoring of wind turbines from a remote location (local control center). However, different wind turbine applications have different requirements in terms of data volume, latency, bandwidth, QoS, etc. This paper proposes a hierarchical communication network architecture that consist of a turbine area network (TAN), farm area network (FAN), and control area network (CAN) for offshore WPFs. The two types of offshore WPFs studied are small-scale WPFs close to the grid and medium-scale WPFs far from the grid. The wind turbines are modelled based on the logical nodes (LN) concepts of the IEC 61400-25 standard. To keep pace with current developments in wind turbine technology, the network design takes into account the extension of the LNs for both the wind turbine foundation and meteorological measurements. The proposed hierarchical communication network is based on Switched Ethernet. Servers at the control center are used to store and process the data received from the WPF. The network architecture is modelled and evaluated via OPNET. We investigated the end-to-end (ETE) delay for different WPF applications. The results are validated by comparing the amount of generated sensing data with that of received traffic at servers. The network performance is evaluated, analyzed and discussed in view of end-to-end (ETE) delay for different link bandwidths.

A new cobalt coordination polymer based on Co(II)-azide chains and a tetrapyridyl ligand: Synthesis, unprecedented topology and magnetism

A new cobalt(II) coordination polymer formulated as [Co2(N3)4(L)]n·4n H2O (1) (L=tetrakis(3-pyridyloxymethylene) methane) was synthesized by a diffusion method, and structurally and magnetically characterized. In compound 1, the Co(II) chains with double end-to-end (EE) azide bridges are interlinked by the tetrapyridyl ligands into a three-dimensional framework. With both Co(II) and L as 4-connecting nodes, the structure represents the first real example of the 4-connected net topology with point symbol (62·74)(64·7·9)2. Magnetic studies demonstrated that the double EE azide bridges transmit antiferromagnetic interactions along the chain.

Pancreatico-duodenectomy and postoperative pancreatic fistula: risk factors and technical considerations in a specialized HPB center.

Postoperative pancreatic fistula (POPF) is a common complication of pancreatic resection. Aim of this study is to identify variables related to the development of POPF, analyze their clinical significance and discuss our current approach to the pancreatico-jejunal anastomosis. A series of 129 patients undergoing pancreatico-duodenectomy (PD) have been analyzed. Patients were divided in two groups: group F, 26 patients who have developed POPF; group NF, 103 patients who have not developed POPF. Demographic, clinical and intraoperative data were compared. Seventy-six patients had an end-to-side (ES) pancreatico-jejuno anastomosis, 53 an end-to-end (EE) anastomosis. Fifteen patients developed grade A fistulas, seven grade B, and four grade C; two patients with grade C fistula died from septic shock. Preoperative bile duct lithiasis, diameter of the pancreatic duct and consistency of the pancreatic stump were significantly different between F and NF groups at multivariate analysis. POPF has been related to clinical and biological parameters: preoperative bile duct lithiasis and challenging pancreatico-jejunal anastomosis (with small pancreatic duct and friable pancreatic stump) are the most prominent according to our experience. As the incidence of POPF seems to be related to technically demanding surgery, we presently reserve the EE anastomosis to the cases in which a friable gland or a very small duct will make a direct anastomosis on the pancreatic duct unreliable. In case of grade C fistulas a total spleen-preserving pancreatectomy should be considered an adequate treatment to prevent the onset of a multi-organ failure or a septic shock if no other treatment seems suitable.

Surgical outcomes of post intubational or post tracheostomy tracheal stenosis: report of 18 cases in single institution.

Tracheal resection and end-to end anastomosis (TRE) is known as standard treatment of tracheal stenosis (TS) and there are various methods to keep ventilation during operation. We reviewed ventilation methods and postoperative outcomes in patients with postintubational (PI) or posttracheostomy (PT) TS. From May 2006 to May 2013, 18 patients with PI or PTTS underwent TRE in our hospital. All patients' records were retrospectively reviewed. The mean duration of intubation and tracheostomy were 14.2 days (range: 2 to 27 days) and 114.9 days (range: 43 to 215 days). The location of stenosis was tube cuffs (n = 10), stoma (n = 6) and double stenosis involving cuff and stoma (n = 2). The mean diameter of stenotic lesion was 5.4 mm (range: 2 to 9 mm. ECMO (n = 4) was performed in critical stenosis. Of two cases with double stenosis, one underwent preoperative endotracheal balloon dilatation and the other underwent TRE with cricoplasty. The overall complication rate was 11.8%. The mean follow-up duration was 14.0 months (range: 0.9 to 56.3 months). Comparing with the literatures, TS treated by TRE in our hospital has shown satisfactory outcomes. To maintain appropriate ventilation for critical stenosis, ECMO could be one of safe methods.

Fret Studies of Conformational Changes in Heparin-Binding Peptides

FRET (Förster Resonance Energy Transfer) was applied to study structural properties of heparin-binding peptides containing the sequence XBBBXXBX where 'X' represents hydropathic or uncharged and 'B' represents basic amino acids. Internally quenched fluorogenic peptides were synthesized containing the fluorescent donor oaminobenzoic acid (o-Abz) and the acceptor dinitrophenyl ethylenediamine (Eddnp) group. Using the CONTIN computational package, distance distributions were recovered from time resolved fluorescence data, associated to end-to-end distances of the peptides. The peptides containing three or four repeat units have random structure in aqueous medium, and the interaction with low molecular weight heparin stabilized short end-to end distances. Experiments in water/trifluoroethanol (TFE) mixtures showed changes in distance distributions compatible with compact conformations stabilized above 40% volume content of TFE in the mixture. Similar changes in distance distributions were also observed for the peptides in interaction with SDS micelles in aqueous suspensions and circular dichroism data revealed alpha-helix formation in the peptides in interaction with heparin, SDS micelles or the co-solvent TFE. The process is dependent on electrostatic and hydrogen bond interactions and the end-to-end distances obtained are smaller than expected for the peptides in linear α-helix conformation, indicating the occurrence of structural arrangements leading to additional decrease in the distances.

Successful Excision of a Suspected Mycotic Transplant Renal Artery Patch Aneurysm With Renal Allograft Autotransplantation

Successful Excision of a Suspected Mycotic Transplant Renal Artery Patch Aneurysm With Renal Allograft Autotransplantation

Integrated FLAG based Energy Efficient Routing with Drop Minimization in MANET

The conservation of energy and the improvement in lifetime of the network has been a challenging task in Mobile Ad hoc Networks (MANET) due to their dynamic and un-predictable behavior and topology change. A route selection and packet drop due to limited buffer(queue) size are two important factor that causes energy consumption by handling retransmission of dropped packets. So many energy aware routing and queue management strategies have been introduced individually. By combining energy based routing with queue management, the lifetime of the network can be increased most effectively. This paper proposes integrated maximum energy based routing with prediction of the route failure by energy estimation and Dynamic queue initialization to reduce packet drop. We modified AODV protocol and drop-tail queue. A Simulation has been performed on NS-2 with the parameter packet delivery fraction, Throughput, endto end delay and number of packets. By comparison planned approach with the old one better result has obtained. General Terms Energy based routing, Queue management, Energy consumption.

Reply to Letter

Nederlof, Nina BSc; Tilanus, Hugo W. MD, PhD; Tran, T. C. Khe MD; Hop, Wim C. J. PhD; Wijnhoven, Bas P. L. MD, PhD; de Jonge, Jeroen MD, PhD Author Information

Diamond: An Improved Fat-tree Architecture for Large-scale Data Centers

With the widespread deployment of cloud services, data center networks are developing toward large-scale, multi- path networks. To support the new trend, some novel network architectures have been proposed, and Fat-tree is one of the most promising architecture and gets a lot of attention because it has good performance on aggregate bandwidth with a simple topology. This paper presents Diamond, an improved Fat-tree architecture for large-scale data centers. Diamond replaces all the aggregation switches of Fat-tree with edge switches and connects directly edge switches to core switches. By this alteration, the average route path and End-to-End (ETE) delay in Diamond are 10% less than that in Fat-tree. We design FAR, a simple and high-efficient routing method for Diamond. In FAR, each switch requires only hundreds of route entries to support a large-scale network with tens of thousands servers, and to build FAR routing tables, switches exchange very few messages. Diamond and its FAR routing are verified through OPNET simulations. 

Surface Plasmon Resonance Coupling Effect of Assembled Gold Nanorods Based on the FDTD Simulation

Much attention has been given to the optical properties of noble metal nanostructures and these are closely related to the size, morphology, and environment of the nanoparticles. In this paper, the influences of structures and assembly modes on the surface plasmon resonance (SPR) of Au nanorods were studied through a finite-difference time-domain (FDTD) simulation on Au nanorod assemblies (dimers and multimers) of different configurations. The simulated optical spectra agree well with the experimental results. The simulated results for the side-by-side (S-S) orientedAu nanorods indicate that the transverse SPR (SPRT) has a slight red- shift, and the longitudinal SPR (SPRL) blue-shifts obviously. For the end-to-end (E-E) orientedAu nanorod dimer, the results indicate that with a decrease in the gap spacing of the E-E orientedAu nanorods, the SPRT does not shift while the SPRL red-shifts obviously. Moreover, a new coupling SPR peak appears in the near-infrared (NIR) region, blue-shifting and enhancing with a decrease in the gap spacing. Based on the spring oscillator model and the polarization of the nanoparticles under an incident electric field, we propose a reason for the SPR shift and the appearance of a new coupling SPR for the Au nanorod assemblies.

Free volume in PEP-silica nanocomposites with varying molecular weight

The influence of confinement in polymer-nanocomposites on free volume and glass transition of the polymer chains was studied. The molecular weight (Mw) of poly(ethylene-alt-propylene) (PEP) was varied from 3k to 200k and so the end-to end distance of the chains at fixed diameter (∼15 nm) and concentration (15%) of the silica nanoparticles increased. Thus the topological confinement increases with increasing Mw. Using hydrophobic PEP and particles functionalized with short organic molecules, we can rule out contributions of permanent adsorption of the chains. DSC showed no change in glass transition temperature. The decrease in the specific heat capacity could be explained by a simple mixing rule. By positron annihilation lifetime spectroscopy, taking properly into account contributions of the silica particles, we rule out an influence of the geometrical confinement on the free volume in the PEP nanocomposites studied here.

Changes of the donor nerve in end‐to‐side neurorrhaphies with epineurial window and partial neurectomy: A long‐term evaluation in the rat model

End-to-side (ETS) neurorrhaphy has been applied in the repair of peripheral nerve injuries and in babysitter procedures. However, the long-term changes of donor nerve and muscle after ETS remain unknown. This study was designed to investigate long-term changes in donor nerve and muscle in a rat model. Sixty Lewis rats were equally allocated into three groups of 20 rats. The peroneal nerve was divided. In Group A, end-to-end (ETE) neurorrhaphy was performed. In Group B, ETS was performed to an epineurial window on the tibial nerve. In Group C, ETS was performed to the tibial nerve with 40% partial neurectomy. The following data were obtained at 6, 12, 18, and 24 weeks postoperatively: latency delaying rate (LDR), amplitude recovery rate (ARR), myelinated fiber counts, muscle force and weight, and cross-sectional area of gastrocnemius muscle fibers. The results showed no significant changes of the donor nerve and muscle in Group B. Nerve regeneration was found in the peroneal nerve, and myelinated fiber number was significantly decreased when compared to the nerve with ETE. In Group C, the myelinated axon number in the peroneal nerve was equivalent to the level in ETE repair. However, function and structure of the donor nerve and muscle were significantly impaired in the early postoperative period. Nonetheless, full recovery was observed 24 weeks after surgery. Both ETS with epineurial window and 40% donor nerve neurectomy showed reinnervation of the recipient nerve without structural and functional changes of the donor system in a long-term follow-up. Partial neurectomy may promote recipient nerve regeneration, but at the cost of donor neuromuscular compromises in the early postoperative period. This study provides long-term evidence for further investigation of ETS in peripheral nerve repair and in babysitter procedures.

Chiral heterometallic 3d–3d azido complex: Synthesis, structure and magnetic properties

Abstract A novel three-dimensional chiral heterometallic 3d–3d azido complex, [Co2Zn(N3)4(pyzc)2]∞(1) (pyzc = 2-pyrazinecarboxylate), was obtained by assembling CoII, ZnII, azido, and pyrazine carboxylate under solvothermal condition. The structure of the complex can be described as end-on (EO) azido, end-to-end (EE) azido mixed bridged alternate Co–Zn chains linked by the 2-pyrazinecarboxylate. Magnetic studies indicate that dominant anti-ferromagnetic coupling interactions exist in the complex.

Synthesis, X-ray crystal structure, and electrochemistry of polynuclear azido-bridged manganese(III) and copper(II) Schiff base complexes

Abstract New azido-bridged [MnIII(salabza)(μ-1,3-N3)]n (1), and [CuII4(salabza)2(μ-1,1-N3)2(N3)2(HOCH3)2],(2) complexes with an unsymmetrical Schiff base ligand, {H2salabza = N,N’-bis(salicylidene)-2-aminobenzylamine}, have been synthesized, characterized by spectroscopic and electrochemical methods, and their crystal structures have been determined by X-ray diffraction. In complex 1, each manganese(III) atom is coordinated with N2O2 donor atoms from salabza and two adjacent Mn(III) centers are linked by an end-to-end (EE) azide bridge to form a helical polymeric chain with octahedral geometry around the Mn(III) centers. Complex 2 is a centrosymmetric tetranuclear compound containing two types of Cu(II) centers with square pyramidal geometry. Each terminal copper atom is surrounded by N2O2 atoms of a salabza ligand, and the oxygen atom of the methanol molecule. Each central copper(II) ion is coordinated with two phenoxo oxygen atoms from one salabza, one terminal azido, and two end-on (EO) bridging azido ligands. The central copper(II) ions are linked to each other by the two end-on (EO) azido groups.

End-to-end versus end-to-side venous microanastomoses in head and neck reconstruction

Venous thrombosis (VT) is the primary reason for microvascular free flaps (MFFs) failure. Different series have addressed the influence of venous anastomosis, end-to-end (ETE) vs. end-to-side (ETS), on this issue in head and neck (HN) microsurgery, but a consensus about the optimal technique to be adopted is still lacking. The aim of this study is to prospectively compare the venous complication rates of ETE and ETS techniques in 422 homogeneously treated patients who underwent MFF for HN oncologic defects between 2000 and 2012 at our Institution. Patients were divided into two groups: Group A (n = 269 patients) receiving an ETE and Group B (n = 153) an ETS venous anastomosis. The choice between the type of venous anastomosis was based on the several variables: availability of adequate caliber recipient veins in the neck, length and caliber of the donor vein, geometry and orientation of the vascular pedicle, and possibility to create a tensionless anastomosis. An ETE anastomosis was always preferred when feasible, while an ETS (performed on the internal jugular vein) was reserved to cases in which the abovementioned considerations contraindicated an ETE. Overall, the MFF failure rate was 3%. Among the 13 failures, five had VT (1.1%): three had received an ETE, and two an ETS. Venous anastomosis re-exploration and failure rates of the two groups were compared by the Chi-squared test showing no statistically significant differences. In conclusion, our data show how ETS venous anastomosis is a safe alternative to ETE whenever the latter cannot be properly accomplished for the previously mentioned contraindications.