A versatile double‐network (DN) hydrogel with two noncovalent crosslinked networks is synthesized by multiple hydrogen bonding (H‐bonding) interactions. The DN hydrogels are synthesized via a ...heating–cooling photopolymerization process by adding all reactants of agar, N‐acryloyl glycinamide (NAGA) and N‐benzylacrylamide (NBAA) monomers, UV initiators to a single water pot. Poly(N‐acryloyl glycinamide‐co‐N‐benzyl acrylamide) (P(NAGA‐co‐NBAA)) with a triple amide in one side group is synthesized via UV‐light polymerization between NAGA and NBAA, forming a strong intermolecular H‐bonding network. Meanwhile, the intramolecular H‐bonding network is formed between P(NAGA‐co‐NBAA) and agars. The sol–gel phase transition of agars at 86 °C generates the molecular entanglement network. Such a double network enables the hydrogel high self‐healing efficiency (about 95%), good shape memory ability, and high mechanical strength (1.1 MPa). Additionally, the DN hydrogel is completely crosslinked by multiple hydrogen bonds (H‐bonds) and the physical crosslinking of agar without extra potential toxic chemical crosslinker. The DN hydrogels find extensive applications in the biomedical materials due to their excellent biocompatibility.
Poly(N‐acryloyl glycinamide‐co‐N‐benzyl acrylamide)/agar double‐network hydrogels crosslinked by multiple hydrogen bonds are synthesized. The double network gives the hydrogel high self‐healing efficiency (about 95%), high mechanical strength (1.1 MPa), and good shape memory ability.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Medical fixing is one of the very important applications of the shape-memory polymer material, and the two important properties of the medical fixing material are that it perfectly fits the body ...during the fixing and easily detaches after being used. As the fixing and detachment are triggered by two independent stimuli in two opposite directions, it is necessary to develop multidirectional triple-shape-memory polymers. In this research, a series of polymer materials composed of trans-polyisoprene (TPI) and paraffin were prepared by melt blending and compression molding, and then the TPI was cross-linked by vulcanization. As a result of the large difference in the melting temperature and crystallization temperature between TPI and paraffin, the obtained polymer materials exhibit a triple-shape-memory behavior. According to the analysis of crystal behavior, microscopic morphology, and mechanical properties of the materials with different paraffin contents and TPI cross-linking density by differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, and dynamic mechanical thermal analysis, the shape-memory behavior of the obtained materials was tunable by the cross-linking density of TPI and the crystallization degree of TPI or paraffin. Compared with the traditional triple-shape-memory material, our samples are prepared in a more facile way and can recover at human body temperature (37 °C). Moreover, our TPI/paraffin material can realize more flexible multidirectional recovery, as well as can be reprogramed and used multiple times. To the best of our knowledge, there are few polymer materials reported, which can realize multidirectional recovery. These unique multidirectional and reprogramable properties will enable the application of this polymer material, especially in the medical fixing materials.
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IJS, KILJ, NUK, PNG, UL, UM
The shape memory thermoplastic polyurethane (TPU) generally exhibits a phase-separated structure, in which the hard segments form the hard domains via hydrogen bonds, and plays an important role in ...shape recovery. However, the physical interaction in the hard domains is always weak, resulting in a permanent deformation and thus decreasing the shape-recovery ability of TPU significantly. In this research, a new type of diol chain extender containing anthracene groups was synthesized, and the photoresponsive anthracene groups were incorporated into the hard segment of TPU. The stability in hard domains and recoverability could be tailored by different UV irradiation times via the photodimerization of anthracene groups, and the shape-recovery ratio and the shape-fixing ratio were still both above 93%, even when the strain reached 270%. More importantly, the shape-free reconfiguration is achieved through the dimerization of anthracene groups under UV irradiation, which achieved free construction of three-dimensional (3D) shapes without templates. Thus, the spontaneous shape change from two-dimensional (2D) to 3D was realized, in combination with melting transition, and the dedimerization of anthracene ensured the recyclability of polyurethane at T = 150 °C. This simple and facile strategy could be used to fabricate the recyclable and photoplasticity shape memory TPU with a high shape-fixing/recovery ratio at large deformation, and it would have a wider range of potential application in stents.
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IJS, KILJ, NUK, PNG, UL, UM
Metastases of nonthyroid malignancies to the thyroid gland are rare, and only sporadic cases have been reported in literature. We present our experience in treating patients with metastases to the ...thyroid gland at Peking Union Medical College Hospital.
The clinical data of 32 patients who presented with secondary thyroid tumors were retrospectively analyzed.
Eleven patients (34.5%) had thyroidectomy.Two patients (6.25%) had tracheostomies to alleviate compression caused by enlarged thyroid tumors.
The most common primary lesion was in the lungs (14/32), followed by the kidney (5/32) and gastrointestinal system (5/32). The interval from the diagnosis of the primary tumor to thyroid metastasis varied from 0 month to 16 years. Ten patients (31.3%) are still alive, and the longest follow-up survival time was 7 years.
Thyroid metastases are rare, and the lung was the most common primary site of origin. It seems that thyroidectomy has not been considered in cases with a high clinical stage of the neoplastic process such as lung cancer.
Based on the adhesive mechanism of mussels, we present a facile strategy to prepare nanocomposite polydopamine–poly(N-acryloyl glycinamide)–graphene oxide (PDA–PNAGA–GO) hydrogels with lots of ...catechol groups in the matrix of hydrogel. The microfibril structure formed by PDA chains enables the hydrogels high stretchability (∼1500%) and toughness (6990 J/m2); the multiple hydrogen bonding interactions and π–π interactions among the PNAGA network and PDA chains also enable a hydrogel perfect self-healing performance. Moreover, GO in the hydrogel can absorb the near-infrared irradiation, resulting in the temperature difference between the surface and bottom area and then a bending deformation (with 40% of actuation degree) of the hydrogel. Besides, the GO can also make the hydrogels electrically conductive, and the self-healing efficiency (∼87% for the first healing) could also be calculated according to the retention rate of conductivity of hydrogel after being healed at 90 °C. The unique properties will enable the PDA–PNAGA–GO hydrogels to be widely used in the field of tissue engineering and soft actuators.
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IJS, KILJ, NUK, PNG, UL, UM
Silicone rubber is a type of elastomer that possesses excellent biocompatibility and a good resistance to high and low temperatures and can be used as the matrix of smart materials in the biomedical ...field. As one of the attractive functions of smart materials, their regional shape transformation behavior under multiple stimuli is very useful. In order to produce silicone elastomers with these characteristics, a special structure such as a Janus structure is usually required. Herein, a novel strategy to prepare a silicone elastic light-triggered actuator with a Janus structure has been developed, which was fabricated
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heterogeneous crosslinking induced by a gradient intensity of UV light due to carbon nanotube (CNT) accretion. By tailoring the geometric shapes, the region and time of the UV irradiation and the location of the stimulus, the Janus membranes can be programmed with multiple types of deformations and exhibit a shape transformation triggered by organic solvent or laser irradiation. Additionally, the membrane can be readily switched between Janus and homogeneous structures due to the reversible dimerization of anthracene, resulting in the reconfiguration of the membrane. Meanwhile, the composite membrane exhibits an excellent self-healing ability at 60 °C, or even room temperature, and can be recycled repeatedly
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the hot-pressing or solution casting methods because of the introduction of reversible imine bonds into the crosslinked networks. This strategy provides significant guidance for the design of self-healable and reconfigurable soft biocompatible actuators, and so forth.
A recyclable silicone elastic light-triggered actuator with reconfigurable Janus structure and self-healable performance is reported, which was fabricated
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heterogeneous crosslinking induced by a gradient intensity of UV light due to CNTs accretion.
We evaluated the efficacy and safety of the modified FOLFOX6 (mFOLFOX6) regimen as a neoadjuvant chemotherapy in gastric cancer patients.
Seventy-three patients with T2-T4 or N+ were enroled. ...Preoperative chemotherapy consisted of three cycles of mFOLFOX6. The primary end points were the response rate and the R0 resection rate. Prognostic factors for overall survival (OS) were investigated using univariate and multivariate analyses.
Sixty-seven (91.8%) patients completed 3 cycles, with grade 3-4 toxicity arising in 33.0%. The radiology response rate was 45.8%. Sixty-seven (91.8%) patients receiving radical surgery showed different levels of histological regression of the primary tumour, with a ⩾50% regression rate of 49.2%. ypTNM stage (HR 4.045, 95% CI 1.429-11.446) and tumours of diffuse and mixed type (HR 9.963, 95% CI 1.937-51.235; HR 8.890, 95% CI 1.157-68.323, respectively) were significantly associated with OS. The pathologic regression rate (GHR; ⩾2/3/<2/3, ⩾50%/<50%) was statistically significantly associated with OS according to a univariate analysis.
Perioperative mFOLFOX6 was a tolerable and effective regimen for gastric cancer. The ypTNM stage was an independent predictor of survival. GHR ⩾50%/<50% could be used as a surrogate marker for selecting a postoperative chemotherapy regimen.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Central lymph node metastasis of papillary thyroid microcarcinoma (PTMC) is common; however, prophylactic central lymph node dissection (CLND) is still controversial because of the possible increased ...morbidity. The purpose of this study is to determine the clinical outcome of patients with cN0 PTMC by central neck dissection.
A retrospective cohort study was conducted on patients with PTMC without preoperative evidence of lymph node disease (cN0), and the outcomes were compared between patients undergoing total thyroidectomy (TT) alone (group A) and patients undergoing TT with CLND (group B).
In this study, 242 patients with cN0 PTMC were included. Group A had 108 patients and group B had 134 patients. During a follow-up of over 60 months, the long-term postoperative complications were equivalent between the two groups. In group B, the presence of involved central neck lymph nodes upstaged 16% of patients to stage III disease, which necessitated additional postoperative radioactive iodine treatment. More patients had recurrences in group A. The rate of reoperation in the central compartment was higher in group A than in group B (8.3% vs 2.2%, P < 0.01).
Prophylactic CLND does not increase long-term postoperative complications and reduces the risk of recurrence in the central compartment.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Electronic fetal heart monitoring is a common method to detect fetal abnormalities used by obstetricians. Effective analysis and diagnosis of cardiotocography during labor not only helps to solve the ...problem of neonatal cerebral palsy caused by fetal distress, but also greatly reduces neonatal mortality. Among the existing analysis algorithms, most of them are based on machine learning to extract and classify the characteristics of cardiotocography. The results which depend on the recognition of features are always unstable. The baseline of fetal heart rate is the most basic characteristic. In this paper, the baseline characteristics of fetal heart rate are firstly extracted, and then the Long Short-Term Memory network is used for segmental classification of fetal heart rate. The results of the experiment show the superiority and efficiency of deep learning in feature extraction, and make it possible for fetal distress detection in computer-aid diagnosis which has greatly reduced the burden on doctors.
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