In both series, the molar ratio of HBA to the other monomers varied from 0 to 5. The thermal properties, degree of crystallinity, and stability of the liquid crystalline mesophase of the copolymers obtained at each HBA ratio were evaluated and compared. Overall, at each HBA content, the DHN-containing copolymer had better thermal properties, but the HQ-containing copolymer exhibited a higher degree of crystallinity and a more stable liquid crystalline mesophase. Furthermore, similar thermal stabilities were observed in both series. The dependence of the molecular dynamics of the TLCPs on the monomer structure was explained using 13C magic-angle spinning/cross-polarization nuclear magnetic resonance spectroscopy. An in-depth investigation of the relaxation time of each carbon revealed that the molecular motions of the TLCPs were greatly influenced by the structures of the monomers present in the main chain. The molecular dynamics of the HQ and DHN monomers in the two series were evaluated and compared.Two series of thermotropic liquid crystal copolymers (TLCPs) with different monomer structures and compositions were synthesized. The copolymers in the first series consisted of 2,5-diethoxyterephthalic acid (ETA), hydroquinone (HQ), and  Thermotropic liquid crystal polymers (TLCPs), which contain a special monomer chemical structure, are already widely used as high-performance commercial engineering polymers owing to their good thermal properties, high strength, high modulus, low viscosity, and other excellent mechanical properties ,2. Many p-hydroxybenzoic acid (HBA), 6-hydroxy-2-naphthoic acid (HNA), naphthalenediol derivatives, and naphthalenedicarboxylic acid isomers [para-substituted carboxyl group or benzene ring, homopolyesters synthesized from monomers such as TPA, HQ, and HBA typically melt at approximately 600 °C [meta-substituted monomer units can provide significantly increased processability. Disadvantageously, this improvement in processability is often accompanied by a significant deterioration of the thermo-mechanical properties.Although interest in TLCPs and their composites has been increasing, to achieve enhanced physical properties, most studies have focused on rigid rod-type TLCPs with completely aromatic monomers in the main chain ,9. In al isomers ,11,12,13y 600 °C . These Ty 600 °C ,16,17. Ty 600 °C ,18. In ay 600 °C ,20. If t13C nuclear magnetic resonance (NMR) chemical shifts is the best method to identify synthesized chemical structures. In addition, 13C-NMR relaxation times in the rotating frame spin-lattice (1ρT) for 13C nuclei, which have low natural abundance, are affected by dipolar interactions with directly bonded hydrogens [13C-NMR 1ρT values are particularly informative because they are directly related to the motion of each carbon in the kHz frequency range. 13C-NMR 1ρT results obtained using cross-polarization (CP) and magic-angle spinning (MAS) have been used to elucidate the molecular dynamics of various chemical structures [13C-NMR 1ρT values is the best method for studying the molecular dynamics of individual 13C atoms in a chemical structure.The measurement of ydrogens . Therefoructures ,23. Ther13C solid-state NMR spectroscopy.The objectives of this study were to: (1) synthesize a two copolymer series using 2,5-diethoxyterephthalic acid (ETA), HBA, and two different diol monomers, namely, HQ and 2,7-dihydroxynaphthalene (DHN); (2) study the effect of the HBA unit on the properties of the ETA/HQ and ETA/DHN copolymers by varying the HBA molar ratio (0–5); and (3) study the molecular dynamics of the two copolymer series using gT), melt transition temperature (mT), and isotropization temperature (iT). Both ETA and DHN have very poor thermal properties, and to compensate for this disadvantage, para-substituted HBA was also used as a monomer. The thermal properties, thermal stability, liquid crystalline mesophase, degree of crystallinity, and molecular dynamics of the synthesized copolymers were investigated while varying the molar ratio of HBA from 0 to 5. In addition, the effect of the molar ratio of HBA on the structures of the polymers in each series was investigated using 13C-NMR spectroscopy. The 1ρT value for each carbon of the dialkoxy groups, C=O groups, and TPA, HQ, naphthalene, and HBA rings in the two series (TLCP-I and -II) was obtained to understand the molecular dynamics. In addition, the dependence of molecular motions on the molar ratio of HBA was investigated using the relaxation times, and the effect of the molar ratio of HBA on carbon mobility was discussed.The copolymers were synthesized using ETA, which contains dialkoxy side groups, and DHN, which is a kinked monomer, to lower the values the glass transition temperature  or TCI  and were used as received. However, common solvents were purified by distillation.1–5) for the TLCP syntheses are shown in The chemical structures of all the monomers (2/3/5 = 1:1:2 (molar ratio)) is detailed here as a representative example. First, 25.42 g (1.0 × 10−1 mol) of ETA (2), 19.42 g (1.0 × 10−1 mol) of 1,4-diacetoxybenzene (3), and 36.03 g (2.0 × 10−1 mol) of 4-acetoxybenzoic acid (5) were placed in a polymerization tube. The mixture was heated under the conditions shown in The TLCPs were synthesized by a melt polymerization method . The monThe obtained solid product was cooled to room temperature, washed several times with acetone, and then dried in a vacuum oven at 80 °C for 24 h to obtain TLCP-I. In most common solvents, the synthesized TLCP was not dissolved at all. In particular, it has not been dissolved at all in various mixed solvents, which have often been used to dissolve TLCP. In almost all common solvents, the synthesized TLCP was not dissolved at all. In particular, it did not dissolve at all in mixed solvents such as phenol/p-chlorophenol/1,1,2,2-tetrachloroethane = 25:40:35 (w/w/w), which were frequently used for TLCP dissolution. As no dissolution was observed, the viscosity could not be measured, as indicated in 2/4/5 = 1:1:2 (molar ratio)) as a representative example. TLCP-II was synthesized using 25.42 g (1.0 × 10−1 mol) of ETA (2), 24.42 g (1.0 × 10−1 mol) of 2,7-diacetoxynaphthalene (4), and 36.03 g (2.0 × 10−1 mol) of 4-acetoxybenzoic acid (5). As a final step to complete the polymerization, the pressure was lowered from 240 to 1 Torr. The subsequent steps were the same as those described for TLCP-I. The monomer composition of TLCP-II is shown in The same synthetic procedures were used to produce each TLCP; therefore, we describe here the preparation of sample II-C  1ρT values were measured by varying the duration of the 13C spin-locking pulse [13C sensitivity. The width of the π/2 pulse used to measure the 13C-NMR 1ρT values was 3.3 μs. The decay of the 13C magnetization in the spin-locking field was followed for spin-locking times of up to 160 ms.Powdered samples were inserted into 4 mm diameter zirconia rotors and then spun at fsufficient speed to avoid the overlap of spinning sidebands. ng pulse . The typ2 atmosphere using DuPont 910 equipment . The samples were heated or cooled at a rate of 20 °C/min. Wide-angle X-ray diffraction (XRD) measurements were performed at room temperature on a Rigaku (D/Max-IIIB) X-ray diffractometer  using Ni-filtered Cu-Kα radiation. The scanning rate was 2°/min over a 2θ range of 2–35°. A polarizing microscope  equipped with a Mettler FP-5 hot stage was used to examine the liquid crystalline behavior. The ChemDradfsw  computer simulation program was used to investigate the three-dimensional (3-D) polymer structures.The thermal properties of the copolymers were determined by differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA), which were conducted under a N13C NMR chemical shifts and 1ρT values were obtained by 13C CP/MAS NMR spectroscopy at a Larmor frequency of ω0/2π = 100.61 MHz using Bruker 400 DSX NMR spectrometers at the Korea Basic Science Institute, Western Seoul Center, Seoul, Korea. The chemical shifts are referenced to tetramethylsilane (TMS).The nd heating were used to obtain thermal properties  using DSC, and the scanning temperature ranges were determined in advance using TGA to prevent thermal decomposition during scanning. The thermal properties of the two TLCP series are summarized in gT, which is known to depend on the flexibility and rigidity of the monomers, reflects changes in chain interactions and the free volume. In other words, the gT is influenced by the segmental motion of the chains and by the substituent size [gT value will be high. In the TLCP-I series, the copolymers were synthesized by varying the HBA molar ratio between 0 and 5. The gT value of the polymer without the HBA was 93 °C, but this value increased to 96 °C when 1 mol of HBA was added. Increasing the HBA amount further to 3 mol decreased the gT value to 83 °C (sample I-D), but the gT value then increases to 87 °C when 4 mol of HBA was used. Finally, with 5 mol of HBA, the copolymer maintained a gT value of 86 °C. The results of the 2ent size . If the gT values of the TLCP-II series showed a similar trend. When 3 mol of HBA was used (sample II-D), the gT value was the lowest (99 °C), whereas, at 4 mol, the gT value increased to 110 °C (sample II-E), which was similar to that obtained with 5 mol of HBA (111 °C). At low ratios of HBA in the random copolymer, the molecular structure was disturbed, resulting in easier chain movement and increased mobility, and consequently, a lower gT. This phenomenon can be explained thermodynamically using the following equation:H is the enthalpy change and ΔS the entropy change. The gT increased. Generally, a block copolymer has a large ΔH and a relatively small ΔS, resulting in an enhancement of the thermal properties, such as an increase of gT [gT values for the TLCP-II series ranged from 99 to 126 °C, depending on the HBA molar ratio. However, when the ratio of HBA increases, a block copolymer (poly(hydroxy benzoate) (PHB)) of HBA itself was formed, and the se of Tg ,29. ThisgT values of the copolymers containing DHN (TLCP-II series) were higher than those of the polymers containing HQ (TLCP-I series). Compared with the HQ monomer, the naphthalene monomer was substituted with nonlinear units at the 2 and 7 positions. There is a large volume of DHN; therefore, the free volume is large, resulting in higher gT values for copolymers with DHN than for those with HQ in all HBA molar ranges [gT of naphthalene increases more than that of HQ.The r ranges ,30. In omT values of the TLCP-I series, which includes HQ, showed a similar tendency to the gT values . Above 4 mol HBA, the mT values were in the range of 256–258 °C, as an excess of HBA monomers, resulted in the formation of a block copolymer of HBA, thus increasing the mT [mT was not observed up to an HBA molar ratio of 2 owing to the flexible dialkoxy groups in ETA and the kinked structure of DHN [mT values were observed. On increasing the HBA ratio from 3 to 5, the mT values gradually increased from 278 to 311 °C. The DSC results for the two TLCP series are shown in The g values . The polg the Tm . In the e of DHN . The floiT values as for the gT and mT values , similar to the behavior observed for mT. The kinked structure of DHN and the dialkoxy substituents of ETA do not promote liquid crystallinity. In contrast, the simple and linear structure of HBA helps to form liquid crystalline mesophases. Hence, when the molar ratio of HBA increased from 3 to 5, the iT value increased from 305 to 343 °C. These values were similar to those of TLCP-I (302–348 °C). This phenomenon can also be explained by the rigidity of the HBA monomer in part of the main chain. The same tendency was observed for the m values . In the mH) and the enthalpy change of the anisotropic-isotropic transition (ΔiH) were very small, as shown in mH were 1.07–2.74 J/g, and ΔiH were 1.32–3.51 J/g, respectively. In the case of TLCP-II, when the number of moles of HBA increased from 3 to 5 moles, the values of ΔmH were 2.66–3.42 J/g and ΔiH was 1.01–2.76 J/g. This result is because the HBA monomer has a random sequence in the melt polymerization process, and the alkoxy side group present in the main chain reduces the effect of enthalpy.The enthalpy changes of the crystal-anisotropic transition , as described above. A DiT value of 362 °C was observed for HBA = 0 mole (sample I-A), but this value decreased gradually from 380 to 344 °C when HBA was increased from 1 to 3 mol. When HBA was further increased to 5 mol, the DiT value increased again to 356 °C. Similar results were observed for the TLCP-II series, with various changes in DiT depending on the HBA ratio. Therefore, to control the deformation owing to thermal decomposition during processing from the melted state, the structure and ratio of the monomers in the copolymer should be carefully selected. The overall DiT results for both series were generally similar. However, higher R600wt values were observed for the TLCP-II series with DHN monomers than for the TLCP-I series with HQ monomers. This difference is because more charcoal is produced at high temperatures from naphthalene derivatives, which contain two benzene rings, than from HQ, which contains one benzene ring. Overall, the reason why the value of R600wt is generally lower than that of the rigid rod-like main chain TLCP is explained by the alkoxy side group in the main chain.The TGA results for the two TLCP series are shown in gT, mT, iT, and DiT) with the molar ratio of HBA are compared in For the two TLCP series, the changes in the overall thermal properties  is included in the main chain, the liquid crystalline mesophase is destroyed, and a liquid crystal texture is not observed . As mentθ = 20° and 30°, indicating a semicrystalline character. The degree of crystallinity (DC) was calculated from Ic, which is the peak area of the crystalline region, and Ia, which is the peak area of the amorphous region, as follows [The wide-angle XRD patterns of the two TLCP series are shown in  follows : DC (%) d and 2θ values of each XRD peak are summarized in The calculated DC values are summarized in mT and iT ranges showing LC mesophase, and the results are shown in XRD peaks were investigated between Similar results were obtained for the TLCP-II series, as the copolymer containing 5 mol of HBA shows a more linear structure than that containing 1 mol of HBA (sample II-B), which is expected to affect the crystallinity. In contrast, when comparing the 3-D structures of the two TLCP series at the same HBA ratio, the TLCP-I structure is more linear compared to the TLCP-II structure, but the structure of the TLCP-II is more spherical. Thus, it was found that the copolymer structures directly affect the crystallinity.13C CP/MAS NMR. The 13C chemical shifts of the TLCP-I and -II series were obtained for the carbons of the alkoxy groups and aromatic rings at room temperature. In the TLCP-I series, for sample I-A, the 13C chemical shifts for CH3 and CH2 of the alkoxy group are observed at 14.79 and 64.69 ppm, respectively, as shown in 13C chemical shifts for the alkoxy group, ETA, HQ, and C=O are similar to those observed in I-A. The 13C chemical shifts for the benzene ring in PHB are located at 126.37, 132.34, and 148.70 ppm. Structural analysis of the TLCP-I and TLCP–II series was carried out by solid-state 13C chemical shifts of CH3 and CH2 are observed at 14.36 and 64.60 ppm, respectively  is the magnetization according to the spin-locking pulse duration t, and I0 is the total nuclear magnetization at thermal equilibrium. The Tρ1 (=1/W) values were obtained from the slopes of the delay time vs. intensity curves, and the results for each carbon in the TLCP-I and -II series are listed in 13C relaxation times in the TLCP-I and -II series are compared according to the molar ratio of HBA. The 13C-NMR 1ρT values for the CH3 and CH2 of sample I-A are 39.2 and 4.4 ms, respectively  have greater 1ρT values than the carbons of the alkoxy group. When the molar ratio of HBA is increased, the 13C-NMR 1ρT values for the alkoxy group, C=O, and the aromatic rings in TPA, HQ, and HBA decrease, as shown in To obtain the function :I(t) = Iectively . The CH313C-NMR 1ρT values for the TLCP-II series are shown in 13C peak for the benzene ring in HBA somewhat overlaps the peak for the aromatic rings of ETA and HQ, as shown in 1ρT values. For C=O in sample II-A, the 1ρT value is remarkably high. Thus, the alkoxy group and C=O in the TLCP-II series have higher mobilities than those in the TLCP-I series. Carbons e and f in sample I-A and carbons g, h, and i in sample II-A have longer relaxation times than the other carbons, as shown in 1ρT values indicate a higher rigidity of the main chains, which implies that there are strong interfacial interactions between the aromatic rings and the polymer main chains and between the alkoxy groups and polymer main chains. The 1ρT values for the TLCP-I and -II series indicate the effect of the HBA molar ratio on the mobility. All of the C atoms in the TLCP-II series have higher mobilities than those in the TLCP-I series.The gT, mT, iT, and DiT values were observed at an HBA molar ratio of 3. The liquid crystalline mesophases showed nematic schlieren textures in both series, but for the TLCP-II series, nematic textures were not observed at HBA ratios lower than 3 owing to the kinked DHN structure in the main chain. The degrees of crystallinity of the TLCP-I series containing the linear HQ monomer were higher than those of the TLCP-II series with the kinked DHN monomer.Copolymers in the TLCP-I series included ETA, HQ, and HBA, whereas those in the TLCP-II series included ETA, DHN, and HBA. Both series were synthesized with varying molar ratios between HBA and the other two monomers (0–5). The thermal properties, liquid crystalline mesophases, and degrees of crystallinity of the polymers in the two TLCP series were investigated and compared. In both the TLCP series, the minimum 13C chemical shifts. From the 1ρT values, the effects of the HBA molar ratio on carbon mobility were determined for the TLCP-I and -II series. The 13C-NMR 1ρT values decreased for all carbon atoms as the molar ratio of HBA monomers bound to the HQ, and DHN rings increased. In the TLCP-I series, the 1ρT values decreased gradually with an increase in the HBA molar ratio, whereas in the TLCP-II series, the 1ρT values decreased more sharply. This difference indicates that the polymers in the TLCP-II series are more rigid than those in the TLCP-I series and that the molar ratio of HBA has a greater influence on the TLCP-II series. Thus, the HBA rings in the TLCP-I series have higher mobility than those in the TLCP-II series. The 13C-NMR 1ρT was dominated by fluctuations in the anisotropic chemical shifts and became shorter when the amplitude of the molecular motions decreased.The chemical structures of the polymers in the TLCP-I and TLCP-II series were confirmed based on the


This year was a weird one, for science and especially for our lives! It will take some time to get back, or better, to enter a new “normality.” While this transition is happening in the different corners of our planet, at different speeds, we are pleased to present you with our last issue of 2020!JOR Spine is becoming the journal to submit in spine‐related research.In spite of this bizarre year, we have received more than 75 submissions (reaching our target!), making this the highest number of submissions across the 3 years that the Journal has been in existence. This indicates that the JOR Spine Early Career Award, with the support of the ORS Spine Section. The award recognizes excellent young investigators in our field and highlights their outstanding work published in JOR Spine. This year looks also to be a particular one, as we had two indivisible winners. We are happy to announce the recipients of this year's award to be Dr Zehra Uruj and Dr Zhen Li for their manuscripts “Spinopelvic alignment predicts disc calcification, displacement, and Modic changes: Evidence of an evolutionary etiology for clinically‐relevant spinal phenotypes” and “ Proinflammatory intervertebral disc cell and organ culture models induced by tumor necrosis factor alpha,” published in the March and September 2020 issues, respectively. We are looking for a same tight competition for the next year's award.We are also extremely happy to announce the second Also, we are excited to highlight this special issue featuring the collected papers from the ORS PSRS Fifth International Spine Research Symposium, “New Horizons in Intervertebral Disc Research,” which took place the 2019 fall at Skytop Lodge in Pennsylvania. This issue features cutting edge reviews and primary research from invited speakers and awardees at the meeting, with a special editorial and introduction by Chitra Dahia, James Iatridis, and Lachlan Smith.Finally, in our effort to involve and to reach out different countries, we are also pleased to announce to our Chinese colleagues and friends, the launch of another “Regional Reviews” series, focusing this time on spine researchers from China, with Guest Editors, Prof. Zhuojing Luo, Prof. Bin Li and Assoc. Prof. Zhen Li.JOR Spine expands and increases its readership and leadership, we are also entering a critical phase in which our initial impact factor will be issued by mid‐2022. This is an important and a unique turning point for the journal and for the whole spine research community as well. Therefore, we would like to thank, in advance, all our submitters and followers for their future nonstop support.As the With our best seasonal greetings and enjoy the issue!


This study aims to investigate possible differences in clinical outcomes between precut and surgeon-cut grafts for Descemet membrane endothelial keratoplasty (DMEK).142 consecutive patients who underwent DMEK were included in the study. 44 patients received precut tissues, and 98 patients received surgeon-cut tissues. Precut grafts were allocated to the patient by the German Society for Tissue Transplantation if available. We compared the outcomes of both groups for changes in visual acuity, central corneal thickness, endothelial cell density, re-bubbling rate, and graft failure rate.p = 0.55, CCT change 118 μm, p = 0.63). There was no statistical difference in endothelial cell density , re-bubbling , and graft failure rate . No primary graft failure occurred in the group of precut grafts.Patients who received precut tissues experienced similar increase in visual acuity (median change 0.4 logMAR) and decrease of corneal swelling (median change 132 μm) compared with those who received surgeon-cut tissues (median VA change 0.3 logMAR, Both methods lead to comparable results for visual acuity, corneal deswelling, endothelial cell density, and re-bubbling rate. A previously described higher graft failure rate for precut tissues could not be confirmed in our study. Thus, we do not see medical reasons against the use of precut tissues. There are several advantages of precut DMEK tissues over surgeon-cut tissues, especially the prevention of graft loss during preparation in the operating theater. Since its first description by Melles [y Melles  in 2006,Besides graft unfolding, the most challenging step is graft preparation directly before the operation. Therefore, the idea of preparing the graft as much as possible in the tissue bank was developed . The aimThose advantages are especially relevant in eye hospitals without an associated eye bank, i.e., centers that do not have the possibility of switching to another graft in case of preparation failure and tissue loss.In Germany, precut tissues have been provided by the German Society for Tissue Transplantation, Hannover, since December 2015.In this study, we searched for possible differences in clinical outcomes of patients who received a precut tissue compared with patients whose graft was prepared by the surgeon directly before DMEK in the operating theater. 142 consecutive patients who received DMEK at the Leipzig University Eye Hospital between April 2016 and December 2017 were included. All grafts were supplied by the German Society for Tissue Transplantation seated in Hannover, Germany. The study was performed as an observational cohort study. Whenever possible, precut tissues were used. Due to limited availability of suited corneas for pre-preparation, not every request for precut tissues could be fulfilled. 44 patients received precut tissues. The other 98 patients received surgeon-cut tissues. All grafts were allocated by the German Society for Tissue Transplantation as available, without knowledge of individual patient parameters. Thus, a pseudo-randomization was achieved.n = 74) for pseudophakic patients or in combination with phacoemulsification and posterior bag lens implantation  for all phakic patients.Operation was performed as DMEK alone  at a temperature between 31 and 37 °C. Before transplantation, donor corneas were deswollen in culture medium K2 , consisting of medium K1 with addition of 6% dextran 500. The culture period was median 22 days with a minimum of 11 days for surgeon-cut and 14 days for precut corneas and maximum 34 days for both types of corneas including 1 to 6 days deswelling time. All tissue manipulations were performed under sterile conditions in laminar air flow with no-touch technique. Microbiological testing of both culture medium and donor tissue was performed, and negative results were mandatory before further processing of the grafts. After verification of sufficient endothelial cell quantity and morphology, grafts were sent to Leipzig University Eye Hospital. In the operating theater, preparation of the Descemet’s membrane via liquid bubble technique as described by Szurman [The procedures performed at the German Society for Tissue Transplantation until delivery to Leipzig were identical to those described above. Additionally, trephination was performed, and Descemet’s membrane with endothelium was nearly completely dissected from the stroma, leaving only a central area adherent . Such prAfter preparation, standard DMEK was performed in both groups as initially described by Melles . All surPatients were advised to lie flat on their backs postoperatively. If significant graft detachment was detected via OCT within the first postoperative days, re-bubbling with 20% sulfur hexafluoride gas was performed. If necessary, this was repeated until complete graft attachment was achieved. Medical treatment consisted of 3 days of intravenous prednisolone as well as topical steroids, antibiotics, and pilocarpine. Topical steroids were tapered monthly and kept once per day for 1 year after operation.Follow-up visits took place 1, 3, 6, and 12 months after operation. Further visits were performed if necessary, especially if immunological reaction or graft failure was suspected. Primary graft failure was defined as permanently persistent corneal edema immediately after DMEK despite correct graft orientation. Secondary graft failure was defined as corneal edema with subsequent deterioration of vision after an initial period of a clear cornea, without observation of any signs of graft rejection or improvement after topical steroids.Postoperative data for visual acuity and central corneal thickness (CCT) were taken from the follow-up visit 6 months after operation. CCT was measured by corneal tomography . Endothelial cell density (ECD) measurements were not routinely performed in all patients. If available, ECD data were taken from the follow-up visit 6 months after operation. ECD was measured using specular microscopy ., Armonk, NY). Categorical variables are presented as numbers and compared with Fisher’s exact test, while continuous variables are presented as median (1st–3rd quartiles) and compared with two-sidedt test. A significant result was defined as p < 0.05. Diagrams were created with Excel® 2013 .Visual acuity, CCT as measured via OCT, ECD, re-bubbling rate, and graft failure rate in both groups were analyzed. In a subgroup analysis, possible differences for these parameters between DMEK and triple DMEK cases were analyzed. Best-corrected visual acuity was converted from decimal to logMAR. Statistical analysis was performed with SPSS® Statistics Software Version 21.0 . Both graft failures in the precut group were secondary graft failures. The first one appeared 16 months after operation and the second one 21 months after operation. Successful re-DMEK was performed in both cases. The graft failure in the surgeon-cut group was a primary graft failure, i.e., despite correctly orientated and attached graft swelling of the patient’s cornea persisted. The case could be rescued with successful re-DMEK as well.We experience graft failures in both groups Table . There ap = 0.5). Postoperative macular edema was seen in 3 cases (7%) in the precut group and in 2 cases (2%) in the surgeon-cut group . There was one (2%) immunologic graft reaction in the precut group and no one in the surgeon-cut group .No significant difference was found in complications between the two groups. Postoperative intraocular pressure elevation was seen in 4 cases (9%) in the precut group and in 6 cases (6%) in the surgeon-cut group  with a greater reduction in the DMEK group. This might be due to the fact that this group comprised pseudophakic bullous keratopathy cases with primarily decompensated corneas. No differences in CCT reduction were found between precut and surgeon-cut tissues within the groups .CCT reduction showed a significant difference between DMEK and triple DMEK (p = 0.55).The above-mentioned three graft failures all occurred in the DMEK group. No graft failure occurred in the triple DMEK group. However, Fisher’s exact test showed no significant difference (Time disjuncture of graft preparation and the actual DMEK procedure have some advantages over graft preparation directly before the operation. Eye hospitals with associated eye bank have the possibility of pre-stripping donor tissue and keeping it in organ culture, which does not seem to affect clinical outcomes . HoweverThe current study compared clinical outcomes of patients who received precut grafts and patients who received surgeon-cut grafts. Our results suggest that the well-known benefits of DMEK as described in larger cohorts –11 can bOur results contradict the previously published results on clinical outcomes of precut DMEK tissues: An observational retrospective cohort study from Freiburg, Germany, found a higher number of graft failures in their precut group. It has to be mentioned that the group which received precut tissues consisted of only 11 patients, while the surgeon-cut group consisted of 453 patients. Precut tissues were prepared at the same site, but preparation was stopped after trephination, and the graft was stored in a deswelling organ culture medium for 1–2 days. The authors suspected the second storage in deswelling media with high molecular dextran and the short storage in saline solution as reason for their results .A retrospective comparative study from Lyon, France, investigated 11 patients that received precut tissues and 22 patients that received surgeon-cut tissues. There was no significant difference in CCT and ECD between both groups 6 months after surgery. There was one graft failure with precut tissues and four graft failures with surgeon-cut tissues .Prospective data are available from a study of 22 patients that received precut tissues and 29 patients that received surgeon-cut tissues. Precut tissues were prepared in the eye bank 1 day before transplantation and stored in organ culture media. Surgeon-cut tissues were prepared directly before surgery. The statistical analysis of both groups showed comparable results for visual acuity outcomes, change in CCT, endothelial cell loss, and graft failure rate . ComparaThere are some limitations of our study: Allocation to either of both study groups was not performed via true randomization. However, precut grafts were provided by the German Society for Tissue Transplantation whenever possible without knowledge of individual patient parameters. Specular microscopy was not performed routinely in all patients, so ECD data were not available for all patients.Presently, widespread use of precut graft is limited mainly because of two practical reasons: Limited availability due to higher work load in the eye bank and significant higher costs. With further acceptance, both factors might be overcome, and the advantages of precut tissues might set the path for them as standard in DMEK preparation for hospitals without an associated eye bank.


Acinetobacter baumannii presents challenges for clinical treatment and causes high mortality in children. We aimed to assess the risk factors and overall mortality for MDR/XDR Acinetobacter baumannii infected pediatric patients.Multidrug resistant (MDR) and extensively drug resistant (XDR) Acinetobacter baumannii infection in the pediatric intensive care unit (PICU) of Shanghai Children’s Hospital in China from December 2014 to May 2018.This retrospective study included 102 pediatric patients who developed MDR/XDR Acinetobacter baumannii clinical isolates were recovered from different specimens including blood, sputum, bronchoalveolar lavage fluid, cerebrospinal fluid, ascites, hydrothorax, and urine. Antibiotic susceptibility test was determined according to the Clinical and Laboratory Standards Institute interpretive criteria. Clinical and biological data were obtained from the patients’ medical records.Acinetobacter baumannii infection were enrolled. The median age was 36  months, and there were 63 male in the case group. The overall mortality rate was 29.4%, while the Acinetobacter baumannii-associated mortality rate was 16.7% . Bloodstream infections occurred in 28 patients (27.5%), and 10 patients (9.8%) among them had central line-associated bloodstream infections . Cerebrospinal fluid (CSF) cultures were positive in 4(3.9%) patients. 14(13.7%) patients got positive cultures in ascites and hydrothorax. Lower respiratory isolates (56/102) accounted for 54.9% of all patients. Non-survival patients appeared to have a lower NK cell activity , higher CD4+ T cell ratio ,and a higher serum level of interlukin-8 pg/mL vs. 0.1 pg/mL, P = 0.01) when Acinetobacter baumannii infection developed. Multivariate logistic analysis indicated that high serum level of Cr  and high BUN/ALB level  were associated with high risk of mortality in MDR/XDR Acinetobacter baumannii infected patients.102 patients with Acinetobacter baumannii infection is a serious concern in pediatric patients with high mortality. Bloodstream and central nervous system infection accounted for high risk of death. Acute kidney injury is associated with high risk of mortality.MDR/XDR  Acinetobacter baumannii is a Gram-negative coccobacillus that has a remarkable ability to acquire antibiotic resistance and that cause persistent nosocomial infections [Acinetobacter baumannii to be multidrug-resistant (MDR) or extensively drug-resistant (XDR) presents therapeutic challenges [Acinetobacter baumannii and higher mortality [fections  The mortfections , 3. The allenges , 5. Invaortality , 7.Acinetobacter baumannii in Southeast Asia were higher compared to other areas [Acinetobacter baumannii bacteremia [The incidence of infections due to MDR er areas , 9, Accocteremia . The procteremia , 12.Acinetobacter baumannii infection [Acinetobacter baumannii infection is responsible for a high mortality rate among neonates in the NICU [Acinetobacter baumannii bacteremia in PICU patients [Acinetobacter baumannii infection in critically ill pediatric patients in China. Thus, the objective of this study was to assess the outcome and risk factor in hospitalized children with multidrug resistant and extensively drug resistant Acinetobacter baumannii infection in a pediatric intensive care unit.In pediatric critically ill patients, underlying diseases, immune deficiency, and invasive operations all contributed to the higher incidence of multidrug resistant nfection . Multidrthe NICU . Accordipatients . HoweverAcinetobacter baumannii infection in the pediatric intensive care unit (PICU) of Shanghai Children’s Hospital in China from December 2014 to May 2018. Colonization was defined as positive culture results from clinical isolated samples  without clinical manifestation of infection.This retrospective study included pediatric patients who developed multidrug resistant and extensively drug resistant Acinetobacter baumannii clinical isolates were recovered from different specimens including blood, sputum, bronchoalveolar lavage fluid, cerebrospinal fluid, ascites, hydrothorax, wound swabs, and urine from immunocompromised pediatric patients with symptomatic clinical infections at least 48 h after PICU admission. Specimens collected from from different specimens were placed in 3 mL BHI broth and incubated at 37 °C with constant rotation for 24 h and were then spread on MacConkey agar. An aliquot of 5 mL nutrient broth was homogenized added to agar, and incubated for 5 min at 22–25 °C. Then spread 100 μL of sample on blood agar and incubated at 37 °C for 24 h. After that, a volume of 100 μL saline peptone obtained from each floor sample was spread on blood agar and incubated at 37 °C for 24 h. Colonies were preliminarily screened by morphology and characterized by oxidase and triple sugar iron tests. The antibiotic susceptibility was determined using the disk diffusion method in our study. The following antimicrobial disks were used: ampicillin-sulbactam (10/10 μg), ceftazidime (30 μg), imipenem (10 μg), gentamicin (10 μg), co-trimoxazole (1.25/23.75 μg), piperacillin (100 μg) and cefepime (30 μg). Susceptibility testing to the tested antibiotics was determined according to the Clinical and Laboratory Standards Institute (CLSI) interpretive criteria for disk diffusion method, as well as the broth dilution MIC measurement [5 microorganisms per cc of urine with no more than 2 species of microorganisms. At least 2 urine cultures with repeated isolation of the same uropathogen (gram negative bacteria or Staphylococcus saprophyticus) with ≥102 colonies/mL in nonvoided specimens. Tracheal aspirate specimens were qualified on a quantification (cfu/mL) from the culture, the colony quantification less than 1×103 cfu/mL was considered as possible colonization.surement . Serial surement . AccordiAcinetobacter baumannii-associated mortality was defined as death caused by Multidrug resistant and extensively drug resistant Acinetobacter baumannii infection but not other pathogen infection. The primary outcome was overall mortality. Secondary outcomes included the Acinetobacter baumannii-associated mortality and the length of hospital stay.Clinical, biological and treatment data were obtained retrospectively from the patients’ medical records. Underlying illnesses at the time of admission to the PICU were classified and pediatric risk of mortality III (PRISM III) scores were measured at the time of PICU admission. Shock was defined according to FEAST study . The ovep < 0.05 in a univariate analysis were included in a multivariate analysis, which was performed by stepwise logistic regression. All statistical analyses were performed with the Statistical Package for the Social Sciences, version 17.0 .Continuous variables were presented as mean ± standard deviation for normal distribution data and as median (interquartile range) for abnormal distribution data. Comparative analysis was conducted using an independent sample nonparametric test. The chi-square test or Fisher’s exact test was conducted. The Mann-Whitney test was used for continuous variables. Variables showing Acinetobacter baumannii in 102 patients were identified, their demographics and clinical features were summarized in Table Acinetobacter baumannii was 0.48 cases/1000 patient-days, and we observed a continually increased distribution of cases during the study period. The overall mortality was defined as the survival status when the patient discharged. In our study, the overall mortality was 29.4% (30/102), while the Acinetobacter baumannii-associated mortality was 16.7% (17/102). In 28 cases (27.5%) surveillance blood cultures became positive after clinical manifestation appeared, while 10 isolates from catheter (9.8%) , 4 cerebrospinal fluid (3.9%) and 14(13.7%) ascites and hydrothorax were identified MDR/XDR Acinetobacter baumannii positive. 19 (18.6%) samples from tracheal aspirate and 37 (36.3%) from sputum cultures for MDR/XDR Acinetobacter baumannii positive. The median age was 36  months and male predominated (61.8%). 51 patients had surgery (50.0%) and 70 treated with corticosteroids (68.6%), all these patients received broad-spectrum antibiotics treatment for more than one week , higher CD4+ T cell ratio , at the same time, a higher serum level of interlukin-8 pg/mL vs. 0.1 pg/mL, P = 0.01) was noticed. The results from logistic regression showed that the risk factors for death among MDR/XDR Acinetobacter baumannii infection including high level of BUN/ALB and renal dysfunction . The resistance rate of cefoperazonesulbactam was 44% and its intermediate rate was 43%.Bacteriological findings are summarized in Fig. Acinetobacter baumannii infection were enrolled. All the patients received active antibiotic treatment within 7 days. Regarding treatment given within 7 days, based on the in vitro susceptibility test, cefoperazone/sulbactam, tigecycline, polymyxin were the recommended antimicrobial agents for XDR Acinetobacter baumannii eradication. The overall mortality rate was 29.4% (30/102), while the Acinetobacter baumannii-associated mortality rate was 16.7% .A total of 102 patients with Acinetobacter baumannii, an aerobic, gram-negative bacillus which is widely distributed in nature, is notorious for its remarkable Ability to acquire antibiotic resistance. As a result, it causes persistent hospital-acquired infections [Acinetobacter baumannii at our facility was 0.48 cases/1000 patient-days, which approximated to the incidence of 0.47 cases/1000 patient-days from reported in ICU patients [Acinetobacter baumannii while MDR/XDR Acinetobacter baumannii strains appeared.fections . In our patients  but lowepatients . PatientAcinetobacter baumannii infection with an incidence rate of 54.9% (56/102). Both blood stream and CNS infection caused relative high mortality, in our research, 12 in 28 bloodstream infection patients and all 4 meningitis patients died. Due to increased invasive operations as well as the severity of primary conditions of critically ill patients, the overall incidence of MDR/XDR Acinetobacter baumannii infection increased.From our single-center data, ventilator-associated pneumonia (VAP) occupied the major complication in pediatric critically ill patients who MDR/XDR Acinetobacter baumannii is resistant to most pediatric antimicrobial agents, including penicillins, most cephalosporins, carbapenems, aminoglycosides, and sulfa drugs. XDR Acinetobacter baumannii tends to develop resistance to multiple antimicrobial agents through degrading enzymes targeting β- lactams, increasing the expression of Ampc enzyme, modifying enzymes targeting aminoglycosides and alteration to the binding sites for quinolones, producing OXA-23 carbapenem enzyme, decreasing the expression of outer membrane pore channel protein, efflux pump system hyperactivity, and loss of PBPs. Additionally, MDR/XDR Acinetobacter baumannii could induce drug resistance through plasmid integration, while causing multiple drug resistance plasmids [Acinetobacter baumannii to beta-lactam antibiotics were more than 75% except for cefoperazone/sulbactam (42%). When it came to the in vitro activities of beta-lactamase inhibitors, sulbactam was superior to clavulanic acid and tazobactam. Sulbactam has good intrinsic antimicrobial activity against multidrug-resistant acinetobacter strains at concentrations readily achievable in human serum [MDR/XDR plasmids , 21. In an serum . As the Acinetobacter baumannii, some in vitro studies have shown that certain drug combinations are synergistic [Acinetobacter baumannii isolates. Fosfomycin, when combined with imipenem, may enhance the inhibition of bacterial cell wall synthesis. So, from this point of view, the combination of fosfomycin and carbapenems in the past few years benefited a number of our patients.Since the safety of children’s medication has been put in an important place, our choice of antibiotics faced a lot of limitations. Although no evidence in the literature that combination therapy is prior to single drug for infection with MDR/XDR ergistic , 24. In ergistic , the comAcinetobacter baumannii was transported together by infiltrating neutrophils. Go Kamoshida et al. [Acinetobacter baumannii exploits human neutrophils by adhering to and inducing IL-8 release for bacterial portage. Acinetobacter baumannii stimulation IL-8 plays a critical role in enhancing the migration of Acinetobacter baumannii -adhering neutrophils, the migration of Acinetobacter baumannii was suppressed when the infiltration of neutrophils was suppressed by inhibiting IL-8 [Acinetobacter baumannii lipopolysaccharide leads the production of the neutrophil chemotactic factor IL-8 and the proinflammatory cytokine TNF-α [Acinetobacter baumannii infected patients, a higher serum level of IL-8 pg/mL vs. 0.1pg/mL) was detected in the non-survival group, this phenomenon might explain that Acinetobacter baumannii in this group seems to spread throughout the body more easily.a et al.  found thing IL-8 . Throughne TNF-α . In our Acinetobacter baumannii are immunostimulatory [+ T cells play important role in the Th1/Th2 paradigm, participate in inflammation [Acinetobacter baumannii (AbOmpA) is a major porin protein in the outer membrane and is partly responsible for apoptosis of eukaryotic cells. Jun SikLee et al [+ T cell differentiation towards a Th1 response. Most biofilms provide a mechanical barrier to phagocytosis much like a capsule. A small number of bacteria become biologically active by migration from the biofilm or by shearing forces that remove small clumps of the biofilm. These bacteria released from the biofilm can induce not only host responses but also act as the seeding colony for the establishment of another infectious focus [+ T cell ratio than survival patients, which revealed that a persistent neutrophil activation and accumulation in tissue that caused inflammation spread.Studies have shown that purified TLR2 ligands from mulatory . CD4+ T ammation , AbOmpA ee et al  co-cultuus focus . In our p = 0.001), which coincide with the results in adult patients.Critically ill patients had increased oxygen consumption, when these patients accompanied with capillary leak syndrome, they often had hydration status resulting in increasing reabsorption of urea by the kidneys, and reduction of ALB, elevation of BUN level can be frequently observed. Current studies highlighted BUN/ALB level as a predictor of 30-day mortality in a large sample of adult patients with hospital acquired pneumonia , and in Our study had several limitations. First, because data were collected retrospectively from medical records, some parameters had to be inferred from the charts. Susceptibility testing had limitations, fosfomycin was not included, which resulted in a lack of antibiotic susceptibility evidence when we made treatment decisions.Acinetobacter baumannii is an important opportunistic pathogen that causes nosocomial infection in PICU with a rather high mortality. The incidence increased these years. Bloodstream and central nervous infection accounted for high risk of death. Increased invasive operations, IL-8 releasing, and persistent neutrophil activation contributed to the risk of death.In conclusion, our study suggests that MDR/XDR- Acinetobacter baumannii infection is a serious concern in pediatric patients with high mortality. Bloodstream and central nervous system infection accounted for high risk of death. Acute kidney injury is associated with high risk of mortality.MDR/XDR


Running-specific prostheses (RSP) are designed to replicate the spring-like behavior of the biological leg in people with a lower limb amputation. Running performance strongly depends on stiffness of the RSP. The aim of this study was to investigate the effects of angle of alignment of the RSP on its stiffness, and how this affects total leg stiffness and the gait pattern during running. Ten able-bodied athletes performed eight trials on a treadmill with running-specific prosthetic simulators, while the alignment of the blades relative to the socket was set in four different angles  during two different step frequency conditions (free and imposed). RSP stiffness, total leg stiffness, residual leg stiffness, and spatiotemporal parameters were measured. In both step frequency conditions, the RSP stiffness decreased linearly with increasing angle of alignment. Able bodied athletes were able to compensate for the decreased RSP stiffness, and keep total leg stiffness almost invariant, by increasing residual leg stiffness through a more straight the knee at initial contact. This study confirms that alignment is an important factor to take into account when optimizing the RSP. Whether the observed compensations are feasible in amputee athletes needs further investigation. Athletes with a lower limb amputation use prostheses that mimic the spring-like behavior of the biological human leg. Human running is seen as a bouncing gait for which the body can be modeled as a simplified spring-mass model . For this study, experimental running-specific prosthetic simulators (RSP) were developed. To make sure that the participant fitted the prostheses and were able to complete the experiment, the following inclusion and exclusion criteria were set: the participants age ranged between 18 and 50 years, weight between 60 and 85 kg, and shoe size was between 39 and 43. In addition, participants needed to be healthy without the use of medication for heart and lungs or physical injuries and they should be able to run for more than 10 min with the experimental prostheses. All participants provided written informed consent prior to the experiment. This study was approved by the local ethics committee.For this study a set of RSP simulators for able bodied athletes was developed . The proThe measurements were performed on a dual belt treadmill with embedded force plates . Participants first learned how to run on the RSPs, both overground and on the treadmill, during two practice sessions before the actual day of the experiment. In the final practice session, the preferred running speed (PS) on the treadmill was determined. On the day of the actual experiment, participants first started with a warming-up of 5 min to accommodate again to the prosthesis. During this warming-up, the preferred step frequency (PSF) was determined while the participants ran for 2 min at their preferred speed with a prosthetic alignment of 0°. During the experiment in total 8 trials were executed. Each participant was asked to run with 4 different angles of alignment of the blade relative to the orthosis  in two different step frequency conditions: imposed and free step frequency. During the imposed condition the PSF at 0° was fixed for all al alignments using a metronome, while during the free condition participants were free to select a different step frequency for different alignments. The 8 experimental trials were divided in four blocks  of two trials . The order of the 4 blocks with different angles of alignment were randomized between participants. The duration of each trial was 2 min, with 5 min rest in between the trials and a short accommodation time with the new alignment before each trial. For safety, participants were supported by an overhead safety harness and were allowed to grab the horizontal bar in front of the treadmill in case they lost balance.The embedded force plates in the treadmill were used to measure the ground reaction force . Motion analysis  was used to measure the 3D-kinematics of blades and leg segments, with cluster markers on the pelvis, thigh, L frame of the orthoses and distal end of the RSP, only for the right leg. The following anatomical landmarks were captured in a static calibration trial: the tip of the toe, calcaneus, lateral and medial malleolus, lateral and medial epicondyle, trochanter major, left and right SIAS, midpoint between the left and right ASIS and the belly button. We additionally captured six landmarks on the RSP: three to indicate the corners of the L-frame of the orthosis and three to indicate the tip, bend and end of the blade .For all outcome measures 100 consecutive steps during the final minute of each trial, during which steady state running pattern was achieved, were analyzed and averaged. The raw kinematics and force plate data were filtered with a low pass 2nd order Butterworth filter, with a cut-off frequency of 20 Hz. Using a 3D inverse dynamics model the kinematics of the pelvis, thigh, shank, and foot were calculated and the net joint moments around knee were determined  and the stiffness of the RSP (KRSP) were the primary outcome measures. Total leg stiffness and RSP stiffness were determined along the line from center of pressure (CoP) to body CoM, which was approximated by the CoM of the pelvis , between the instant of touchdown and the instant at which maximal vertical GRF was reached (0) and total leg length throughout ground contact  at initial contact and the length throughout ground contact. The distance between the most proximal point of the RSP spring and the CoP along the dimension of interest represented the length of the RSP spring.To estimate Ks), stride time (ts), contact time (tc), flight time (tf), angle of attack of the leg (θ), and residual leg stiffness (Kres). Average step frequency (steps/min) was calculated as the number of GRF peaks during the 2 min trials divided by 2. Contact time and flight time were determined with a vertical GRF threshold at 50 N. A vertical GRF above 50 N was set as contact time and a vertical GRF lower than 50 N was set as flight time. The stride time was set from initial contact till next initial contact of the right blade. Kres was calculated by: tot and KRSP was calculated with a linear curve fit. These outcome measures were used to calculate Kres. In addition, knee joint stiffness (Kknee) and knee angle at initial contact (φknee) were analyzed to explain potential changes in Kres  the first sample during every stance face was taken. Angular displacement of the knee was defined as the change in knee angle relative to the touchdown knee angle. The angle of attack (θ) was calculated as the angle between the total leg length vector at initial contact and the vertical  separately. The within factor was angle of alignment . In case there was a significant main effect of alignment, a p = 0.225, p = 0.016, All 10 participants successfully performed all experimental conditions. During the imposed step frequency trials, all participants were able to synchronize average step frequency to the imposed PSF, within an error margin of 2.5%. Mean PSF was 161.1 steps/min (±10.3). The preferred speed ranged between 8.0 and 9.5 km/h. For the step frequency imposed condition, no significant difference in step frequency between the four angle of alignments was found (RSP), stiffness of the residual leg (Kres), and the total leg stiffness (Ktot) at four different alignment angles during the step frequency imposed condition. The effect of angle of alignment was significant for all three stiffnesses calculated, Ktot (p = 0.011), KRSP (p = 0.000), and Kres (p = 0.000). Ktot and Kres increased linearly (p = 0.025 and p = 0.000), whereas KRSP showed a significant linearly decreasing contrast (p = 0.000) when the angle of alignment increased.p = 0.023). The angle of attack decreased linearly from 13.7 ± 1.3° to 12.5 ± 1.4° when the angle of alignment increased (p = 0.017). s, tc, and tf). During this condition the step frequency was imposed. No significant effect of angle of alignment was found for stride-, contact-, and flight time .knee) and knee angle at initial contact is shown in Figure 7. Changing alignment resulted in a significant linear decrease of the knee angle at initial contact (p = 0.003). The knee angle at initial contact decreased from 17.7 ± 5.2° to 13.3 ± 7.2°. There was no significant effect for the knee joint stiffness (p = 0.092).The effect of angle of alignment on the knee joint stiffness (Kp = 0.000) and residual leg stiffness (p = 0.002), but there was no significant effect for the total leg stiffness (p = 0.946). The RSP stiffness showed a significant linear decrease while the alignment angle increased (p = 0.000), whereas the residual leg stiffness showed a significant linear increase (p = 0.001).The total leg stiffness, stiffness of the RSP and stiffness of the residual leg during the free step frequency condition are shown in p = 0.027). The angle of attack significantly decreased from 13.3 ± 1.8° to 12.9 ± 1.8° when the angle of alignment increases (p = 0.006). s, tc, and tf). Stride time increased linear (p = 0.013) from 0.75 ± 0.05 s to 0.77 ± 0.05 s when the angle of alignment increased. Contact time tended to increase with alignment angle but this effect did not reach significance (p = 0.062), although post hoc a significant linear contrast could be found. Flight time did not change significantly (p = 0.205).p = 0.003). The knee angle showed a significant decrease (more knee extension) from 18.0 ± 5.0° to 13.1 ± 7.1°. For the knee joint stiffness, no significant difference between the four angles of alignments was found (p = 0.355).The primary aim of this study was to investigate whether the RSP stiffness depends on the angle of alignment of the RSP and how this affects total leg stiffness and running pattern. This effect was tested in two conditions, (1) a step frequency imposed condition to assess the effect of alignment independently from possible changes in leg angle of attack and (2) a step frequency free condition to include potential adaptations of the athletes to this manipulation in terms of changing leg angle of attack and gait pattern. The results reveal that the effects of angle of alignment in both conditions was almost similar. Therefore, we'll first discuss the general effects of angle of alignment and subsequently discuss the specific differences in the effects in both step frequency conditions.As hypothesized, the stiffness of the RSP showed a significant linear decrease when the angle of alignment increased during both step frequency imposed and free condition , 6A. StiAn important limitation of previous studies  remains constant  constant as we expected that the effect alignment might be confounded by gait adaptations, such as changes in loading rate, step length, and angle of attack. Surprisingly, very little changes in the gait pattern between the step frequency free and imposed conditions were observed. This can be explained by the fact that participants compensated for the considerably decrease of RSP stiffness by increasing residual leg stiffness in both the free and imposed step frequency condition. Small differences between these conditions might be attributed to the influence of the alignment angle on the angle of attack.When the position of the tip of the blade relative to the socket rotates backwards, when the alignment angle is increased, the total leg vector (from CoP to CoM) becomes oriented more vertical when no additional changes in joint configurations are made. Indeed the angle of attack decreased slightly with increasing alignment angle in our experiments. According to the spring-mass model step frequency is a function of total leg stiffness and angle of attack (Blickhan, There are some limitations in this study that should be taken into account when interpreting our findings. First, we included a relatively small number of participants in our study who were not used to running with prosthetic simulators. Participants only had two practice sessions to get used to running on the RSP with different alignment angles. Although all participants felt comfortable with running on the prosthetic simulators, it might take more time to really master this skill. This may affect the current results by introducing greater variability in the running pattern within and between participants. Nevertheless, our set up seems sufficient to reveal the mechanical effects of alignment on RSP stiffness during running. The effects of alignment on RSP stiffness were clear and consistent between trials and could be reproduced in both step frequency conditions. Moreover, the results confirm previous studies that investigated this topic in controlled bench test environments.Finally, and most importantly, we did not include athletes with a lower limb amputation but able-bodied participants using prosthetic simulators. While we believe that the direct mechanical effects of alignment on RSP stiffness, as shown in this study, are independent of study population, the observed gait adaptations might not be similar. As shown previously by Oudenhoven et al. , amputeeProsthetic alignment substantially affects prosthetic stiffness and imposes gait adaptation to the user. Thus, if an optimal prosthetic stiffness is selected for the amputee athlete not only finding the right RSP stiffness category is essential but also the alignment of the blade relative to the socket needs to be taken into account. The specific gait adaption of lower limb amputees to changes in RSP stiffness that accompany alignment changes need further investigation.https://dataverse.nl/dataset.xhtml?persistentId=hdl:10411/0JFYGF.Data from this study are available at: All participants provided written informed consent prior to the experiment. This study was approved by the local ethics committee of the Faculty of Behavioral and Movement Sciences of Vrije Universiteit Amsterdam.AG participated in the design of the study, carried out the data collection, participated in data analysis, and drafted the manuscript. HH participated in design of the study, participated in data analysis, and critically revised the manuscript. All authors gave final approval for publication and agree to be held accountable for the work performed therein.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


The benefits of the use of cold recycling mixtures (CRMs) in pavement rehabilitation are associated with both the reduction of natural resource consumption by replacing them with recycled materials and the reduction of energy consumption during their production and paving. The evolution of the stiffness of CRMs in road construction and the fatigue life of pavements with CRM base layers are still being investigated. In this paper, CRMs with 1% cement content, called bitumen-stabilized materials with bitumen emulsion (BSM-Es), were examined. Mixtures that were differentiated in terms of Reclaimed Asphalt Pavement (RAP) content, as well as the amount and type of bitumen emulsions, were subjected to indirect tensile stiffness modulus (ITSM) tests at 5 °C, 13 °C, and 20 °C. The thermal sensitivities of the BSM-E mixtures were analyzed. BSM-E mixture stiffness modulus levels at various temperatures were determined using a statistical approach. On the basis of the results obtained, a discussion on the mechanistic-empirical design of flexible pavements with BSM-E base layers is presented. The potential benefits of using BSM-E materials in road construction in certain aspects of pavement life are indicated. In the era of limited availability of natural resources and growing awareness of environmental issues, cold recycling mixtures (CRMs) are gaining popularity in terms of pavement base layer construction. The main advantages of this technology are the reduction of costs, energy consumption, and greenhouse gas emissions in comparison with conventional hot mix asphalt (HMA) production ,2.The properties of CRMs depend on the qualitative and quantitative selection of their components, which are Reclaimed Asphalt Pavement (RAP), virgin aggregates, bitumen emulsion or foamed bitumen, water, and active filler. Depending on the applied combination of binding agents, various types of cold recycling mixtures can be distinguished, such as cement-treated materials (CTMs) with cement as the only binding agent, cement–bitumen-treated materials (CBTMs) containing bitumen emulsion or foamed bitumen with a ratio of residual bitumen (B) to cement (C) less than or equal to one (B/C ≤ 1), and bitumen-stabilized materials (BSMs) with a residual bitumen content of approximately 3% and a maximum amount of active filler  equal to 1% (B/C ≥ 1) .While CTMs are considered to be bound materials with high stiffness, rigidity, and brittleness ,6,7, bitThe quantitative and qualitative selection of ingredients plays an extremely important role in developing the mechanical and durability properties of CBTM and BSM mixtures, as reported by many researchers ,15,16,17The aspects of fatigue behavior, as well as the cracking resistance of cold recycling mixtures, are considered complex and have not been fully investigated ,20,21,22According to the second hypothesis, presented by Ebels , the serThe research presented in this paper consists of laboratory testing and discussion on the mechanistic-empirical design of flexible pavements with base layers consisting of bitumen-stabilized materials with bitumen emulsion (BSM-E). The experimental program focuses on the determination of the stiffness modulus (ITSM) of BSM-E mixtures at 5 °C, 13 °C, and 20 °C. Based on the obtained results, the thermal sensitivity and stiffness levels for BSM-E mixtures at various temperatures were characterized. In the second part of the paper, the fatigue life of flexible pavement with BSM-E base layers was determined according to the AASHTO 2004 pavement design procedure. An assumption was made that the BSM-E mixture retained its homogeneity in its entire service life . The calculations performed for the pavement structures with BSM-E base layers were compared to those performed for reference structures with CBTM base layers used on site in Poland.Eight types of BSM-E mixtures were designed. Differentiation of the mixtures was made in terms of the amount of RAP , as well as the amount and type of bitumen emulsion used. Additionally, one reference CBTM mixture with 50% RAP, 3.0% cement and 3.0% bitumen emulsion addition was designed.Grading curves of the BSM-E mixtures were designed using 50% and 70% RAP 0/31.5 mm, derived from milling and wearing and base asphalt courses originally containing dolomite 0/11 and basalt 11/16 aggregates. The average bitumen content in the RAP was determined to be 5.0% by its aggregate weight (PN-EN 12697-1). In order to meet the grading criteria presented in the international standards for BSMs , virgin Two types of slow-setting cationic bitumen emulsions with 60% residual bitumen content  and the cement type CEM II/B-S 32.5 R (EN 197-1) were used to prepare the BSM-E mixtures. The amount of cementitious binder was set to a constant 1% of the mixture mass. The optimum moisture content (OMC) for mixtures was determined in accordance with the modified Proctor moisture–density relationship test procedure (PN–EN 13286-2). The OMC was set to 6.8% for BSM-E mixtures containing 70% RAP and 7.6% for BSM-E mixtures containing 50% RAP. The OMC of the CBTM mixture was set to 5.0%. The mixture compositions of the BSM-E mixtures and CBTM mixture are listed in The BSM-E and CBTM mixtures were mixed and compacted at ambient temperatures (25 °C). The test specimens, with a height of 63.5 mm ± 3.5 mm and a diameter of 101.6 mm, were compacted using a Marshall hammer by applying 75 blows per side, according to national requirements . Perfora3 to 2.138 Mg/m3 for mixtures containing 70% RAP in the mineral mixture and from 2.144 Mg/m3 to 2.160 Mg/m3 for mixtures containing 50% RAP. The average bulk density of the CBTM mixture specimens was 2.207 Mg/m3.Bulk densities of the BSM-E specimens ranged from 2.092 Mg/mA UTM-25 universal testing machine was used to carry out stiffness modulus tests (ITSM) at 5 °C, 13 °C, and 20 °C in an indirect tensile configuration (IT-CY) according to PN-EN 12697-26. A target deformation value of 5 μm was selected in accordance with national instructions  in orderThe Catalogue of Typical Flexible and Semi-rigid Pavements [P = 50 kN load and q = 850 kPa contact pressure.Design of the flexible pavement with a BSM-E base layer was carried out according to fixed pavement structures presented in the national design and construction guide avements . The mechi), Poisson’s ratio (νi), and modulus of elasticity (stiffness) (Ei) at the equivalent temperature of 13 °C were specified for each pavement layer. The stiffness modulus of the traditionally used CBTM mixtures was set to 1500 MPa, and the Poisson’s ratio was set to 0.30. The value of 1500 MPa was the stiffness modulus value, which is recommended for calculations in the Polish guidelines for CBTM mixtures [The comparison of the fatigue lives was carried out between flexible pavement structures with base layers constructed with BSM-E and CBTM mixtures. Both the BSM-E and CBTM layers were considered as flexible. In accordance with the national design guide recommendations , the thimixtures . There imixtures , althougThe results of the ITSM tests at 5 °C, 13 °C, and 20 °C, presented in To evaluate statistically significant differences in the BSM-E stiffness modulus values, one-way analysis of variance (ANOVA) using Statgraphics Centurion 18.1.06 software was performed. By means of the F-test, it was concluded that there was a statistically significant difference between the ITSM mean values at the 5% significance level for each testing temperature. Based on the stiffness modulus values presented in In the case of the BSM-E mixtures with 50% RAP and 3.0% bitumen emulsion content, a significant decrease in the value of the ITSM stiffness modulus at 20 °C was observed. Such a tendency was not observed for the BSM-E mixtures with 70% RAP content.It can be assumed that this reduction of the stiffness is related to the loss of cohesion of the mixtures with low contents of bitumen emulsion  and relatively low contents of RAP. Although RAP has so far been mainly treated as a black rock in cold recycling mixtures, it is not without significance that the old binder surrounding the RAP particles could still take part in binding the aggregates together during compaction . Ebels  reportedAs mentioned in S is the ITSM stiffness modulus at temperature t and ITSMA and ITSMB are parameters depending on the BSM-E mixture characteristics. The fitting parameters of the regression curve for the BSM-E mixtures are presented in In order to quantify the temperature dependency of the BSM-E mixtures, the following equation was proposed:2 values presented in 2 = 0.9659 – 0.9983). The 50%_3.0%E1 mixture was the exception, with an R2 value of 0.8918. Regression curves for the BSM-E mixtures with 50% RAP and 3.0% bitumen emulsion signifficantly differed from those obtained for other mixtures as a result of a significant drop in the stiffness modulus value at a temperature of 20 °C (cohesion loss). The regression curve slope values (represented by ITSMA) described the gradient of stiffness modulus change as a function of the testing temperature; the higher the slope (ITSMA) value, the more temperature-sensitive the BSM-E mixture was. Based on the calculated ITSMA values, it can be stated that all the BSM-E mixtures containing type E2 bitumen emulsion with a 70/100 binder  were characterized by a higher temperature dependency than corresponding mixtures containing type E1 bitumen emulsion with a 50/70 penetration grade binder. In comparison with the CBTM mixture, the BSM-E mixtures presented higher ITSMA values, which stood for a higher sensitivity to changes in the test temperature.Considering the RStatistical analysis of the results was performed to evaluate the level of BSM stiffness at the three test temperatures . The ITSM test results, divided into three groups, were evaluated using statistical data analysis tools (Statgraphics Centurion 18.1.06 software). Probability distribution fitting was conducted, and box plots were created to illustrate the dispersion of the obtained ITSM values in each group. Statistical parameters of the tested statistical samples are presented in p-value > α = 0.05). The general stiffness levels of the BSM-E mixtures were defined as stiffness modulus values tempS, for which the probability of getting a lower ITSM value was approximately equal to 5% (P (X < tempS) ≅ 0.05).Based on the application of the Shapiro–Wilk test, it was concluded that at the adopted level of significance α = 0.05, there were no grounds for rejecting the hypothesis that the analyzed ITSM results in all three samples came from the normal distribution  was created  and single points that represent the average ITSM values for the designed BSM-E mixtures at temperatures of 5 °C, 13 °C, and 20 °C. It can be seen that the specified tempS values were lower than the laboratory-tested average ITSM values for the BSM-E mixtures (except for the results obtained for the BSM-E mixtures with 50% RAP and 3.0% bitumen emulsion at 20 °C).It can be observed that for both variants of the pavement structure, pavement life was determined by the permanent  deformation criterion. The results of calculations of the flexible pavement structure with a base layer of a BSM-E mixture indicated a significant reserve of the required pavement life (over 200%) for all traffic categories. The obtained numbers of equivalent single axle loads (100 kN) to failure for pavements with a BSM-E layer were approximately three to five times greater than those calculated for pavement structures with a CBTM mixture characterized by a stiffness modulus equal to 1500 MPa. Such a significant overdesign of the pavement structures with BSM-E encouraged authors to propose alternative design solutions. For technological reasons, in the case of traffic categories KR1 and KR2, the thickness of the asphalt layer packet had not been changed. The analysis of the fatigue life of category KR1–KR2 pavement structures led to a conclusion that the use of BSM-E base layers could bring significant benefits in terms of the extended service life and reduction of possible maintenance and rehabilitation cost of local roads with light traffic loading. Alternative design solutions for flexible pavements with BSM-E base layers in medium traffic categories (KR3–KR4) are shown in The main goal of creating pavement structure alternatives was to obtain similar values of pavement life for both basic and alternative design solutions while ensuring construction criteria was followed. In that case, the incorporation of the BSM-E layer allowed authors to propose the reduction of the suggested thicknesses of asphalt layer packets by 2 cm for KR3 as well as for the KR4 traffic category. It can be observed that the values of the tensile stresses at the bottom of the asphalt layers decreased by approximately 40% for the KR3 traffic category and 20% for the KR4 traffic category, in comparison with the basic pavement solutions with CBTM mixtures. The potential possibility of reducing the thickness of asphalt layer packets in the case of medium traffic category roads without negatively affecting pavement life has unquestionable benefits in terms of construction material savings, as well as construction, maintenance, and rehabilitation cost reduction.In order to introduce alternative solutions for high traffic categories (KR5–KR7) that are not included in the design guide , the resDue to the reduced amount of cement, BSM-E mixtures exhibit 50–60% lower stiffness modulus values than CBTM mixtures in which a 3% cement addition is applied;The thermal sensitivities of the BSM-E mixtures depend on the type of bitumen emulsion used. Thermal sensitivities for the BSM-E mixtures are higher in comparison with CBTM mixtures, which may indicate that base layers made of CBTM do not exhibit the properties of flexible layers, but rather manifest behavior similar to rigid materials;tempS were determined at three testing temperatures: temp5S = 4000 MPa at 5 °C, temp13S = 2700 MPa at 13 °C, and temp20S = 2070 MPa at 20 °C;Based on statistical analysis, assuming a 5% probability of obtaining lower stiffness modulus results, the following stiffness levels of BSM-E mixtures Assuming the validity of the BSM-E behavior hypothesis that a layer’s stiffness modulus increases during the initial period of pavement exploitation, and the material does not exhibit brittle cracking and a loss of initial stiffness, the constant BSM-E stiffness modulus value of 2700 MPa can be adopted for pavement design calculations;The adaptation of a higher stiffness modulus for BSM-E layers (2700 MPa) in comparison with CBTM layers (1500 MPa) is possible due to the expected difference of material characteristics from rigid and more prone to shrinkage and fatigue cracking for CBTMs to flexible and more crack-resistant BSM-E layers;The mechanistic-empirical pavement design calculations showed that, in the case of light traffic categories KR1–KR2, the application of BSM-E mixtures in base layers may bring potential benefits in terms of extended pavement life and the durability of local roads;For medium traffic categories (KR3–KR4), the thicknesses of asphalt layers presented in the national requirements can be reduced without negatively affecting the pavement life, which can contribute to the reduction of construction material use.The following conclusions can be drawn, based on laboratory test results and pavement design analysis:The laboratory testing and pavement design results should be confirmed and complemented by a real scale analysis. Falling weight deflectometer (FWD) tests are recommended to be conducted in order to analyze pavement response and determine the back-calculated stiffness modulus of the BSM-E layer in certain time intervals. Such tests are crucial to verify the assumption of increased cracking resistance and flexibility of BSM-E base layers.


Material and Methods. Single crowns, bridges, and full-arch rehabilitations were included. The selection process was achieved by reviewing data from the prosthetic laboratory and excluding cases in which zirconium and full-ceramic coating restorations were used. A total of 154 restorations were included . All the complications encountered, and the solutions applied, were explained.  Long-term clinical data on the success and complication rates of monolithic or minimally veneered zirconia implant-supported restorations are lacking. Hence, the purpose of this retrospective clinical study was to analyze the complications of monolithic or partially veneered zirconia implant-supported restorations up to 5 years follow-up.  A total of 93 restorative units had a follow-up of between 24 and 60 months, and 61 restoration units had a follow-up of between 12 and 24 months. A total of 7 complications were encountered . The technical complication rate was 2.08% (one case of minor chipping in one prosthetic unit); regarding the mechanical complications, four decementations (8.33% of the cases) and two screw loosening (4.17% of the cases) were encountered.  Considering the limitations of this study, it can be concluded that monolithic or partially veneered zirconia implant-supported restorations have a good clinical behavior during a follow-up period of up to 5 years. Zirconium (Zr) is a periodic table metal with properties common to the group of metals in terms of resistance and optical and chemical behavior.In the past, metal-ceramics have been the restorative material of choice for tooth- and implant-supported fixed prostheses . AttemptRestorations with a zirconia core and ceramic veneer are widely used with good clinical results for both teeth and implants , 4. In aHowever, the upper-anterior region has higher esthetic demands, so a cut-back technique can be used on the buccal surface of the restorations to veneer feldspathic porcelain in this region. Even after adding this ceramic layer, the risk of chipping is lower, since it is only placed in nonfunctional areas .Additionally, the increased use of computer-aided design and computer-aided manufacturing (CAD-CAM) technology has also improved the cost-benefit ratio. Another important factor when choosing this material is that it causes less wear on the opposing dentition than any other suitable restorative material , 13. HowThe null hypothesis tested was that implant-supported crowns, bridges, and full-arches made of monolithic or partially veneered zirconia have high success rates (over 90%).For this study, patients who consented to receive single crowns, bridges, and full-arch prostheses of monolithic or partially veneered zirconia from 2013 to May 2019 were reviewed. Patients of all ages and with different prosthetic needs at two different private clinics located in Bilbao and Vitoria (Spain) participated in the study .Implant placement and prosthetic protocols were carried out in the same clinical way by two skilled operators (MD and DC). Patients who underwent treatments with implant-supported prostheses ranging from single crowns to fixed partial dentures and full arches were included. Participant selection was conducted by reviewing the data of the clinic history of the patient and including those cases restored with monolithic zirconia and buccal ceramic-veneered zirconia restorations. The following data were considered: age, sex, number of prosthetic units, crowns or bridges, number of abutments and pontics, cantilever units, anterior or posterior, use of monolithic or partially veneered zirconia, zirconia trademark, use of an occlusal splint, time in mouth from placement to the last examination, mechanical and technical complications , and its solutions. The exclusion criteria were as follows: teeth-supported prosthesis, peri-implantitis in some of the implants that supported the prosthesis, implant-supported restorations made of any material other than monolithic or buccal ceramic-veneered zirconia, and restorations which had not been cement-screw-retained.Tapered bone and tissue level Klockner implants were inserted . The implant position was based on a previous prosthetic-guided planning and an exhaustive clinical and radiologic examination. All implant-supported restorations were planned to be hybrid cement-screw-retained. In all the cases, cone beam computed tomography (CBCT) images in combination with three-dimensional (3D) planning software were used . All implants were placed with an open flap procedure and following a drilling protocol according to the recommendations of the manufacturer.2 or ISQ < 65), a healing time of 4 up to 6 months was maintained.A healing time of 8 weeks was applied. If guided bone regeneration procedures were carried out simultaneously to the implant placement, or primary stability values were not enough , prosthetic treatments were performed. The standard clinical procedure for placement of implant-supported prostheses with the one-step pick-up technique and with individual tray was applied. The obtained casts were scanned; next, the design was developed using the Trios software  and later milled in acrylic material . These preliminary restorations served to check esthetics and occlusion. Then, the test result was sent back to the dental laboratory technician for rescanning and virtually superimposing onto the previous design using the same software .Finally, the final structure was milled in monolithic zirconia  according to the performed clinical modifications with a minimum thickness of 0.5 mm. If feldspathic porcelain would be added on the buccal side, a last intraoral test was achieved with the zirconia milled restoration with the buccal cut-back applied, and finally, it was sent back to the laboratory for finishing. All reconstructions were fabricated by the same dental technician in a private laboratory.Before placing the restoration, a try-in occlusion check was performed. If any adjustment was done, restoration was sent back to the laboratory for polishing. For single crowns, hybrid cement-screw retention with antirotational cementing abutments with at least 2 mm of gingival height was used. In bridges, and full arches, nonengaging titanium bases with 1 mm of gingival height and 3.5 mm of cementing surface  were used for hybrid cement-screw-retained restorations.2 according to the manufacturer's recommendations. The screw access hole was closed with flowable composite .The crowns were cemented on the abutment outside of the mouth with a Maxcem Elite™ Self-Etch, Self-Adhesive Resin Dental Cement . Then, in all cases, restorations were screwed into the implant at 30 N/cmPatients were followed up at one month, 6 months, and finally each year except in cases requiring more attention, for example, patients with periodontal diseases who need shorter periodic follow-ups .In this routine recall sessions, clinical and radiographic examination with bitewings and periapical radiographs was performed, and mechanical (decementations or screw loosening) and/or technical complications (chipping or fractures) occurred were written in the clinic history.Due to sample heterogeneity and the impossibility of performing analytical statistics, descriptive statistics were performed and all data were collected in an Excel file, and statistical analysis was performed with computerized software .The study analyzed 154 restorations, including 34 pontics and 8 cantilevers  in 48 patients (26 men and 22 women) between the ages of 20 and 83 (mean age 56.3 years) , yieldinOf these restorations, 80 were posterior, 16 anterior, and 58 full-arch. An overview of all included zirconia implant-supported restorations is given in The follow-up period ranged from 24 to 60 months for 93 prosthetic units and 12 to 24 months for 61 prosthetic units. A total of 7 complications occurred. Five of the complications occurred in the group with a follow-up from 24 to 60 months (94.62% of success rate per restoration and 76.19% per case), and the remaining two complications belonged to the group with a follow-up from 12 to 24 months (96.72% of success rate per restoration and 92.59% per case). There was a single case of minor chipping that occurred in one prosthetic unit out of all the placed with partially veneered zirconia, which was resolved by polishing the ceramic surface, as it was only a minor chipping without exposing the zirconia core.2. All these complications are detailed in Regarding mechanical complications, four decementations occurred, which were resolved by recementation; the screw loosened in two implant-supported splinted restorations, which were fixed by retightening the screws at 30 N/cmThis study investigated the complications of implant-supported crowns, bridges, and full arches of monolithic or partially veneered zirconia. The null hypothesis tested must be accepted for single crowns (anterior and posterior) and for posterior crowns when this group is analyzed in ratios per case.This success rate is consistent with clinical studies such as that of Degidi et al., with 88.2% success rates in restorations placed on implants with conical abutments . HoweverIn this study, only 4 of 49 patients that were rehabilitated with implant-supported FDPs used an occlusal splint. An occlusal splint was prescribed only in patients with bruxism and various joint and/or muscle disorders but not as a general measure to prevent restoration fracture.Most studies published on zirconia describe ceramic-veneered restorations. The most commonly reported technical problem in these cases was a minor ceramic delamination or chipping. Nevertheless, it should be noted this chipping rate is very similar to that reported in the latest published reviews comparing this material with implant-supported metal-ceramic crowns . This reIn all of the studied cases in this research, the restorative material in contact with opposing teeth was monolithic zirconia, since the feldspathic ceramic was only placed on the buccal surface of the upper teeth. The opposing teeth characteristics  were not selected as exclusion criteria to choose the final sample of the study, and this could be a limitation. However, when a prosthetic complication was detected, the opposing teeth were registered. In this sense, only one technical complication occurred—one case of minor chipping in a buccal feldspathic porcelain-veneered crown (tooth 1.1) on an upper full-arch implant-supported rehabilitation. In this case, the antagonist was a natural teeth arch without any restoration and with a mutually protected occlusal scheme with anterior guidance.Regarding decementation and screw loosening, multiple factors could have affected: type of cement employed, size of the cementable abutment, passive fit of the restoration, and occlusal forces –22. NeveIn respect of screw loosening, both cases observed were splinted posterior restorations. In theory, this could make the screw loosening more difficult. However, the higher difficulty to achieve passive fit in FDPs is well known. Hence, the lack of passive fit could have been the cause of this complication. However, a new screw loosening was not observed after retightening in successive recall sessions.Another property of monolithic zirconia is its lower abrasion rate of the opposing tooth compared with other ceramics , 13. In Furthermore, one medium- or long-term problem of monolithic zirconia is its low-temperature degradation (LTD) related to hydrothermal aging; this could cause the material to transform spontaneously from the metastable tetragonal phase to the monolithic phase. This change could affect the mechanical properties of zirconia. This initial phase transformation would facilitate that of adjacent particles because of the increase in the associated volume, thereby increasing stress in these grains and causing microcracking. Microcracks would create a path for water to penetrate the ceramic. The mechanism by which oral environmental factors  affect the transformation rate is not yet clear . DespiteThe retrospective nature of the present study and the different observation periods are its main limitation.in vitro studies have been conducted in this field, a greater number of clinical studies are needed with a longer follow-up period to confirm the results of the present study.Considering the limitations of this study, but taking into account the use of a high number of restorations, long follow-up, and use of the same working protocols, we could affirm that monolithic or partially veneered zirconia is a material with good clinical behavior on implant-supported restorations in follow-up periods of up to 5 years. However, although many


We highlight the gaps in our knowledge in relation to our understanding of the structure and synthesis of starch, and argue that the building block-backbone model takes accurate account of both structural and biochemical data.Starch is a water-insoluble polymer of glucose synthesized as discrete granules inside the stroma of plastids in plant cells. Starch reserves provide a source of carbohydrate for immediate growth and development, and act as long term carbon stores in endosperms and seed tissues for growth of the next generation, making starch of huge agricultural importance. The starch granule has a highly complex hierarchical structure arising from the combined actions of a large array of enzymes as well as physicochemical self-assembly mechanisms. Understanding the precise nature of granule architecture, and how both biological and abiotic factors determine this structure is of both fundamental and practical importance. This review outlines current knowledge of granule architecture and the starch biosynthesis pathway in relation to the  Since the discovery around 1940 that starch is composed of the two polysaccharides amylose and amylopectin, the molecular branched structure of the latter has been a subject of intense research. In 1940, Meyer and Bernfeld  found thbuilding block backbone model proposed by Bertoft 3−) residues on chains impart strong anionic charges which tend to repel neighboring phosphorylated oligosaccharides. It has been proposed that such repulsion opens and hydrates the α-glucan chains making them more susceptible to amylolytic attack [The enzymes involved in covalent addition of phosphate moieties onto α-glucan chains of amylopectin  are indic attack . In addic attack . Phosphoc attack ; GWD attc attack ,248. Thec attack . It is nChlamydomonas the phosphorolytic reaction of SP is stimulated by DPE [DPE and SP act on α-glucans and are implicated in the starch granule initiation pathway (see above). In addition, both enzymes have cytosolic counterparts which are likely involved in the turnover of transitory starch ,250. Thed by DPE . Hwang ed by DPE  showed tMany of the enzyme classes involved in starch biosynthesis discussed in the above sections are coordinated and regulated in a variety of ways, from gene expression to various post-translational mechanisms including protein phosphorylation and redox modulation. The relationship between the formation of various protein complexes and amylopectin structure is unclear. However, many protein-protein interactions confer metabolic advantages, such as mediating substrate channeling , making building block backbone model as opposed to the more traditional cluster model. We argue that a holistic approach to understanding starch biosynthesis using structural analysis data to guide enzymology studies, and vice versa, mutually benefits both fields. Ultimately, we cannot make sense of the various enzymatic reactions and understand their roles without an accurate picture of the fine structure of the starch granule at the molecular, as well as higher order levels. In addition, we propose that both physical and biochemical analysis data of amylopectin fine structure are best described by the building block backbone model. We reviewed current knowledge of the many enzyme classes involved in starch biosynthesis with the intention of assigning their roles (where known) within the context of the structural motifs in the building block backbone model. Despite progress in many areas, important questions remain to be resolved. Beyond the initial linear structures produced during granule initiation we no nothing of the next immediate stages of granule formation involving branching, debranching and elongation. What limits granule size, particularly in storage starches? Despite an abundance of knowledge of enzymatic reactions and the smaller scale structures they produce  we do not know the biological factors and/or self-assembly mechanisms responsible for higher order structures such as blocklets and growth rings. Most of the enzymes involved in amylopectin biosynthesis appear to operate within heteromeric protein complexes, and whilst discussion of these complexes is beyond the scope of this review, it is worth noting that we remain ignorant of the mechanisms by which these protein complexes define amylopectin structure.The intention of this review is to integrate current knowledge of the pathway of starch biosynthesis and starch structure within the context of the