Collagen fabrics as biomaterials

Tissue-engineered implants require appropriate biomaterials to serve the required physical function of the tissue being repaired or replaced while facilitating remodeling of the implant. We report on the development of implantable fabrics manufactured from continuous collagen threads. The collagen threads are formed by extrusion of native, acid-extracted bovine colagen into a buffered solution of polyethylene glycol, followed by rinsing and air drying. The high manufacturing rate of such threads permits the production of colagen fabrics of various configurations. The fiber diameter can be controlled, and threads with dry diameters as low as 25 mum have been produced. Braids and bundles of collagen threads implanted as a replacement of the anterior cruciate ligament in a dog model were completely remodeled into host tissue by 12 weeks. Knitted collagen fabrics implanted in a rat abdominal repair model prevented herniation, and connective tissue ingrowth was observed within the fabric by 12 weeks.     

The influence of seed packaging and fruit color on feeding preferences of American robins

We investigated the role of seed packaging (division of total seed volume among individual seeds) and fruit color in determining feeding preferences of American Robins (Turdus migratorius). Experiments were conducted using artificial fruits with either 8 small plastic beads or a single large one with equivalent volume. Other fruit characters were held constant. As predicted, large seeds were voided rapidly by regurgitation, resulting in higher pulp consumption rates for large-seeded fruits than for small-seeded ones, whose seeds were passed through the gut. Most birds apparently used this difference in profitability as a choice criterion: four of seven preferred large-seeded fruits. That three individuals did not do so suggests that birds may differ in their ability to perceive minor differences in fruit profitability, or to use them as choice criteria. Pulp color was also important: blue fruits were preferred by all seven birds. This preference was surprising, since Robins commonly feed on red fruits in the field.     

Preparation of green colorimetric pH sensor using Humulus lupulus L. (common hop) biomolecular extract for sweat monitoring

Novel smart cotton diagnostic assay was developed toward onsite sensing of sweat pH variations for possible medical applications such as drug test and healthcare purposes. Humulus lupulus L. extract was obtained according to previously reported procedure. As reported by high-performance liquid chromatography (HPLC), the extract demonstrated the presence of hop acids, prenylchalcones, and prenylflavanones, which is responsible for the colorimetric changes. The extract was applied to cellulose fibers employing potassium aluminum sulfate as mordant. This was observed by the formation of mordant/xanthohumol nanoparticles onto cotton surface. The absorption spectra and CIE (Commission Internationale de l'Eclairage) Lab screening of the prepared cotton assay showed colorimetric changes in association with hypsochromic shift from 600 nm to 433 nm upon exposure to sweat simulant fluid (pH < 7). The biochromic activity of the xanthohumol-finished cotton depends mainly on the halochromic performance of the xanthohumol chromophore to show a colorimetric switch from yellow to white owing to intramolecular charge transfer in the xanthohumol molecule. No substantial defects were detected in gas-permeability and stiffness of the treated fabrics. Satisfactory fastness was approved for the xanthohumol-dyed diagnostic cotton assay.     

Effects of cryopreservation with a newly-developed magnetic field programmed freezer on periodontal ligament cells and pulp tissues

The purpose of this study was to evaluate the effects of long-term cryopreservation on the isolated human periodontal ligament cells (PDL) and pulp tissues. In the first part of study, 10 freshly extracted teeth were selected and divided into two groups. In the cryopreserved group, the teeth were frozen for 5 years using a programmed freezer combined with a magnetic field, known as Cells Alive System “CAS”. As for the control group, freshly extracted teeth were used. In each group, extracted PDL tissues were cultured and gene expression and protein concentration of collagen type I, alkaline-phosphatase (ALP) and vascular endothelial growth factor (VEGF) was compared between the two groups. In the second part, pulp tissues were obtained from 10 mature and immature third molars which were freshly extracted or cryopreserved for three months. Expression of VEGF and nerve growth factor (NGF) mRNAs and the protein concentration in the supernatant were investigated. Results indicated that long-term cryopreservation with the use of CAS freezer cannot affect the growth rate and characteristics of PDL cells. There was no significant difference in VEGF expression and VEGF and NGF protein concentration of pulp cells derived from cryopreserved teeth with immature apex and control group with mature root formation. Finally, proper PDL regeneration and appropriate apexogenesis after transplanting magnetically cryopreserved immature tooth was clinically confirmed. These findings demonstrate that teeth banking with the use of magnetic field programmed freezer can be available for future autotransplantation as a treatment modality for replacing missing teeth.     

Mesophilic batch anaerobic co-digestion of pulp and paper sludge and monosodium glutamate waste liquor for methane production in a bench-scale digester

This paper presented results from anaerobic co-digestion of pulp and paper sludge (PPS) and monosodium glutamate waste liquor (MGWL). A bench-scale anaerobic digester, 10 L in volume was developed, to operate under mesophilic (37 ± 2 °C) batch condition. Under versatile and reliable anaerobic conduct, high efficiency for bioconversion of PPS and MGWL were obtained in the system. The accumulative methane yield attained to 200 mL g⁻¹ VS_added and the peak value of methane daily production was 0.5 m³/(m³ d). No inhibitions of volatile fatty acids (VFAs) and ammonia on anaerobic co-digestion were found. pH 6.0-8.0 and alkalinity 1000-4000 mg CaCO₃/L were got without adjustment. This work showed that there was a good potential to the use of PPS and MGWL to anaerobic co-digestion for methane production.     

Pollution control in pulp and paper industrial effluents using integrated chemical–biological treatment sequences

The main objective of the present study was to improve the quality of pulp and paper industrial wastewater of two local mills RAKTA and El-Ahlia, Alexandria, Egypt, and to bring their pollutant contents to safe discharge levels. Quality improvement was carried out using integrated chemical and biological treatment approaches after their optimization. Chemical treatment (alum, lime, and ferric chloride) was followed by oxidation using hydrogen peroxide and finally biological treatment using activated sludge (90 min for RAKTA and 60 min for El-Ahlia effluents). Chemical coagulation produced low-quality effluents, while pH adjustment during coagulation treatment did not enhance the quality of the effluents. Maximum removal of the tested pollutants was achieved using the integrated treatment and the pollutants recorded residual concentrations (RCs) of 34.67, 17.33, 0.13, and 0.43 mg/l and 15.0, 11.0, 0.0, and 0.13 mg/l for chemical oxygen demand (COD), biochemical oxygen demand (BOD₅), tannin and lignin, and silica in RAKTA and El-Ahlia effluents, respectively, all of which were below their maximum permissible limits (MPLs) for the safe discharge into water courses. Specific oxygen uptake rate (SOUR) and sludge volume index (SVI) values reflect good conditions and healthy activated sludge. Based on the previous results, optimized conditions were applied as bench scale on the raw effluents of RAKTA and El-Ahlia via the batch chemical and the biological treatment sequences proposed. For RAKTA effluents, the sequence was as follows: (1) coagulation with 375 mg/l FeCl₃, (2) oxidation with 50 mg/l hydrogen peroxide, and (3) biological treatment using activated sludge with 2,000 mg/l initial concentration and 90 min hydraulic retention time (HRT), while for El-Ahlia raw effluents, the sequence was (1) coagulation with 250 mg/l FeCl₃, (2) oxidation with 45 mg/l hydrogen peroxide, and (3) biological treatment using activated sludge with 2,000 mg/l initial concentration and 60 min HRT. In conclusion, results confirmed that the application of the proposed sequential treatments removed almost all COD, BOD₅, high molecular weight compounds, and silica from RAKTA and El-Ahlia influents and produced high-quality effluents, thus achieving the main objective of this study.     

Optimization of cellobiose dehydrogenase production by Schizophyllum commune and effect of the enzyme on kraft pulp bleaching by ligninases

The effects of various parameters on cellobiose dehydrogenase (CDH) production by Schizophyllum commune AS 5.391 were investigated. Among different carbon and nitrogen sources tested, dewaxed cotton powder and diammonium hydrogen phosphate produced the highest titers of CDH. S. commune AS 5.391 produced CDH only when grown on cellulosic substrates but the lignin-related compounds veratryl alcohol and guaiacol had no effect on CDH production. The optimum pH for CDH production was 4.5. Addition of succinate and Tween 80 to the medium significantly improved the enzyme yield. Optimized culture conditions were obtained and the highest level of CDH was 150 U/l. CDH could facilitate kraft pulp lignin degradation by ligninases. The influence of CDH on kraft pulp bleaching by ligninases was also studied.     

正畸矫治对上颌外伤切牙牙髓活力的影响

目的:研究正畸矫治对上颌外伤切牙牙髓活力的影响。方法:选取我院正畸科2006～2011年期间的病例60例,并按上颌切牙有无外伤史分为正畸外伤组和正畸无外伤组两组;选取我院牙体牙髓科2008-2011年期间上颌切牙有外伤但未行RCT(Rootcanal treatment)的病例30例,设为外伤无正畸组组。对三组间上颌切牙所患牙髓坏死的机率进行比较。结果:正畸外伤组与正畸无外伤组有显著性差别(P<0.01),正畸外伤组与外伤无正畸组亦有显著性差别(P<0.05)。而正畸无外伤组与外伤无正畸组没有显著性差别(P>0.05)。结论:正畸治疗患者中,有严重牙周损伤史的上颌切牙患牙髓坏死的机率要明显高于无外伤史的上颌切牙。     

地下滴灌下土壤水势对毛白杨纸浆林生长及生理特性的影响

在6、7年生三倍体毛白杨(triploid Populus tomentosa)纸浆林中研究了地下滴灌(SDI)下不同土壤水势(-25、-50、-75kPa,即灌溉起始阈值)对林木生长及生理特征的影响。结果表明:与不灌溉(CK)相比,SDI使6、7年生林分的生产力分别平均提高24%和28%;其中,-25 kPa使6年生林分的生产力达到39.90 m3hm-2a-1,较CK极显著提高43.5%(P<0.01)。各水势处理间,-25 kPa的生产力在林分6年生时分别较-50和-75 kPa极显著提高20%和31%(P<0.01),在7年生时分别提高13%和14%(P>0.05)。能在毛白杨速生期内(4—7月)大幅提高土壤含水率(20和50 cm处分别平均提高35%和27%)、树干日平均液流速率(46%,SFmean)、黎明前叶水势(41%,ψpd)是SDI促进林木生长的重要机制。灌溉起始水势阈值的差异对毛白杨SFmean和ψpd无显著影响(P>0.05)。3个水势处理中,-25 kPa的平均SFmean和ψpd均最高,且其能使根系活动剧烈的表土层(0—20cm)的水分有效性有最大幅的提高,这可能是其对林木生长有最大促进作用的主要原因。综上,应在毛白杨纸浆林培育中大力推广SDI,并在应用时可将距滴头10cm、地下20 cm处的土壤水势达到-25 kPa作为灌溉起始阈值。另外,在与试验地环境相似地区栽植毛白杨时,应于4—7月灌溉,8—10月一般可不灌溉。     

Angular orientation of trabecular bone in the femoral head and its relationship to hip joint loads in leaping primates

The elastic properties and mechanical behavior of trabecular bone are largely determined by its three-dimensional (3D) fabric structure. Recent work demonstrating a correlation between the primary mechanical and material axes in trabecular bone specimens suggests that fabric orientation may be used to infer directional components of the material strength and, by extension, the hypothetical loading regime. Here we quantify the principal orientation of trabecular bone in the femoral head and relate these principal fabric directions to loading patterns during various locomotor behaviors. The proximal femora of a diverse sample of prosimians were scanned using a high-resolution X-ray computed tomography scanner with resolution of better than 50 mum. Spherical volumes of interest were defined within the femoral heads and the 3D fabric anisotropy was calculated using the mean intercept length and star volume distribution methods. In addition to differences in bone volume and anisotropy, significant differences were found in the spatial orientation of the principal trabecular axes depending on locomotor behavior. The principal orientations for leapers (Galago, Tarsius, Avahi) are relatively tightly clustered (alpha(95) confidence limit: 8.2; angular variance s: 18.2 degrees ) and oriented in a superoanterior direction, while those of nonleapers are more variable across a range of directions (alpha(95): 16.8; s: 42.0 degrees ). The mean principal directions are significantly different for leaping vs. nonleaping taxa. These results further suggest a relationship between bone microstructure in the hip joint and locomotor behavior and indicate a similarity of loading across leapers despite differences in kinematics and phylogeny.