Potential Use of Quantum Dots in Flow Cytometry

QDs may offer significant advantages in environmental and bead-based applications where the target cells need to be discriminated above background fluorescence. We have examined the possible applications of QDs for flow cytometric measurements (FCM) by studying their excitation - emission spectra and their binding to paramagnetic beads. We labelled beads with either QDs or a commonly-used fluorochrome (FITC) and studied their fluorescence intensity by FCM. Flow cytometric comparisons indicated that the minimum fluorophore concentration required for detection of QDs above autofluorescent background was 100-fold less than for FITC.     

Raman Spectroscopy of Anhydrous and Hydrated Calcium Aluminates and Sulfoaluminates

Recent investigations have revealed the great potential of Raman spectroscopy for the characterization of clinker minerals and commercial Portland cements. The usefulness of this technique for the identification of anhydrous, hydrated, and carbonated phases in cement‐based materials has been demonstrated. In the present work, the application of micro‐Raman spectroscopy for the characterization of the main clinker phases of calcium aluminate cements and calcium sulfoaluminate cement is explored. The main stable hydrated phases as well as several important carbonated phases are investigated. Raman measurements on the following phases are reported: (i) pure, unhydrated phases: CA, C₁₂A₇, CA₂, C₂AS, cubic‐C₃A, C₄AF, and C₄A₃; (ii) hydrated phases: ettringite, monosulfoaluminate, and hydrogarnet (C₃AH₆); (iii) carboaluminate phases: hemicarboaluminate and monocarboaluminate. The present results, which are discussed in terms of the internal vibrational modes of the aluminate, carbonate, and sulfate molecular groups as well as stretching O–H vibrations, show the ability of Raman spectroscopy to identify the main hydrated and unhydrated phases in the aluminate and sulfoaluminate cements. The Raman spectra obtained in this work provide an extended database to the existing data published in the literature.     

Dunaliella salina microalga pressurized liquid extracts as potential antimicrobials

In the present work, the antimicrobial activity of different pressurized liquid extracts obtained from Dunaliella salina microalga was tested against several microorganisms of importance for the food industry (Escherichia coli, Staphylococcus aureus, Candida albicans, and Aspergillus niger). Different solvents (hexane, petroleum ether, hexane, and water) and extraction conditions (40, 100, and 160 degrees C) were tested. Results showed that the best antimicrobial activity was obtained for each solvent at the highest extraction temperature (160 degrees C). Likewise, the extraction yield followed the same trend, i.e., increasing with extraction temperature and was at a maximum when ethanol was used as an extraction solvent. Water extracts had the lowest extraction yields. In general, the best results in terms of antimicrobial activity were obtained using petroleum ether and hexane, although ethanolic extracts also showed good antimicrobial activity. Because the main antimicrobial activity of the extracts was against bacteria, the extracts can be considered to be specifically antibacterial. The extracts were analyzed by gas chromatography-mass spectrometry in order to identify the compounds responsible for activity. Fifteen different volatile compounds as well as several fatty acids (mainly palmitic, alpha-linolenic, and oleic acids) that could have been responsible for the antimicrobial activity were identified in the extracts. beta-Cyclocitral, alpha- and beta-ionone, neophytadiene, and phytol were identified among other volatile compounds; all of these compounds have previously been described as antimicrobial agents.     

Effect of lactose standardization of milk using low-concentration factor ultrafiltration: Effect of reducing the lactose-to-casein ratio on the properties of milled-curd Cheddar cheese

The pH of cheese is determined by the amount of lactose fermented and the buffering capacity of the cheese. The buffering capacity of cheese is largely determined by the protein contents of milk and cheese and the amount of insoluble calcium phosphate in the curd, which is related to the rate of acidification. The objective of this study was to standardize both the lactose and casein contents of milk to better control final pH and prevent the development of excessive acidity in Cheddar cheese. This approach involved the use of low-concentration factor ultrafiltration of milk to increase the casein content (～5%), followed by the addition of water, ultrafiltration permeate, or both to the retentate to adjust the lactose content. We evaluated milks with 4 different lactose-to-casein ratios (L:CN): 1.8 (control milk), 1.4, 1.1, and 0.9. All cheesemilks had similar total casein (2.3%) and fat (3.4%) contents. These milks were used to make milled-curd Cheddar cheese, and we evaluated cheese composition, texture, functionality, and sensory properties over 9 mo of ripening. Cheeses made from milks with varying levels of L:CN had similar moisture, protein, fat, and salt contents, due to slight modifications during manufacture (i.e., cutting the gel at a smaller size than control) as well as control of acid development at critical steps (i.e., cutting the gel, whey drainage, salting). As expected, decreasing the L:CN led to cheeses with lower lactic acid, residual lactose, and insoluble Ca contents, as well as a substantial pH increase during cheese ripening in cheeses. The L:CN ratio had no significant effect on the levels of primary and secondary proteolysis. Texture profile analysis showed no significant differences in hardness values during ripening. Maximum loss tangent, an index of cheese meltability, was lower until 45 d for the L:CN 1.4 and 0.9 treatments, but after 45 d, all reduced L:CN cheeses had higher maximum loss tangent values than the control cheese (L:CN 1.8). Sensory analyses showed that cheeses made from milks with reduced L:CN contents had lower acidity, sourness, sulfury notes, and chewdown cohesiveness. Standardization of milk to a specific L:CN ratio, while maintaining a constant casein level in the milk, would allow Cheddar cheese manufacturers to have tighter control of pH and acidity.     

Capillary electrophoresis separation of rosemary antioxidants from subcritical water extracts

In this work, the possibilities of the combined use of subcritical water extraction (SWE) and capillary electrophoresis (CE) are established through the separation of antioxidants from rosemary (Rosmarinus officinalis L.). A new CE method is developed that allows the separation of different antioxidants found in the SWE fractions. The CE method is reproducible, efficient and fast, allowing the analysis of complex rosemary extracts in less than 16 min. The CE method is compared with a published reversed-phase high-performance liquid chromatography (RP-HPLC) procedure, both using diode-array detection. The main advantages of CE compared with HPLC are its higher resolving power and its different selectivity, which is demonstrated to be useful for the detection of some very polar compounds that cannot be analyzed by RP-HPLC. Moreover, the possibilities of the CE approach for following the degradation of antioxidants is also demonstrated. To our knowledge, this is the first work showing the high potential of the combined use of SWE and CE.     

A cooperative coevolutionary approach dealing with the skull–face overlay uncertainty in forensic identification by craniofacial superimposition

Craniofacial superimposition is a forensic process where photographs or video shots of a missing person are compared with the skull that is found. By projecting both photographs on top of each other (or, even better, matching a scanned three-dimensional skull model against the face photo/video shot), the forensic anthropologist can try to establish whether that is the same person. The whole process is influenced by inherent uncertainty mainly because two objects of different nature (a skull and a face) are involved. In previous work, we categorized the different sources of uncertainty and introduced the use of imprecise landmarks to tackle most of them. In this paper, we propose a novel approach, a cooperative coevolutionary algorithm, to deal with the use of imprecise cephalometric landmarks in the skull–face overlay process, the main task in craniofacial superimposition. Following this approach we are able to look for both the best projection parameters and the best landmark locations at the same time. Coevolutionary skull–face overlay results are compared with our previous fuzzy-evolutionary automatic method. Six skull–face overlay problem instances corresponding to three real-world cases solved by the Physical Anthropology Lab at the University of Granada (Spain) are considered. Promising results have been achieved, dramatically reducing the run time while improving the accuracy and robustness.     

Trp89 in the lid ofHumicola lanuginosa lipase is important for efficient hydrolysis of tributyrin

To determine whether Trp89 located in the lid of the lipase (EC 3.1.1.3) fromHumicola lanuginosa is important for the catalytic property of the enzyme, site-directed mutagenesis at Trp89 was carried out. The kinetic properties of wild type and mutated enzymes were studied with tributyrin as substrate. Lipase variants in which Trp89 was changed to Phe, Leu, Gly or Glu all showed less than 14% of the activity compared to that of the wild type lipase. The Trp89Glu mutant was the least active with only 1% of the activity seen with the wild type enzyme. All Trp mutants had the same binding affinity to the tributyrin substrate interface as did the wild type enzyme. Wild type lipase showed saturation kinetics against tributyrin when activities were measured with mixed emulsions containing different proportions of tributyrin and the nonionic alkyl polyoxyethylene ether surfactant, Triton DF-16. Wild type enzyme showed a V_max=6000±300 mmol·min⁻¹·g⁻¹ and an apparent K_m=16±2% (vol/vol) for tributyrin in Triton DF-16, while the mutants did not show saturation kinetics in an identical assay. The apparent K_m for tributyrin in Triton DF-16 was increased as the result of replacing Trp89 with other residues (Phe, Leu, Gly or Glu). The activities of all mutants were more sensitive to the presence of Triton DF-16 in the tributyrin substrate than was wild type lipase. The activity of the Trp89Glu mutant was decreased to 50% in the presence of 2 vol% Triton DF-16 compared to the activity seen with pure tributyrin as substrate. Wild type lipase and all mutants except Trp89Glu had the same affinity for the substrate interface formed by 15.6 vol% tributyrin in Triton DF-16. The Trp89Glu mutant showed a lower affinity than all the other lipase variants for the interface of 15.6 vol% tributyrin in Triton DF-16. The study showed that Trp89 located in the lid ofH. lanuginosa lipase is important for the efficient hydrolysis of tributyrin and that this residue plays a role in the catalytic steps after adsorption of the lipase to the substrate interface.     

从过程洞察灵活性——回首25年前的房屋项目

二战以后,丹麦常用的建筑方法是带有十字承重墙的多层建筑,但该设计体系并不能很好地适应其后的建筑改造。因此丹麦住房与建设署于1983年颁布了条例来鼓励3～5层的非营利性住房的技术革新,以适应未来新的用户需求,增加建筑的灵活性。2012年春天,丹麦科技大学DTU管理学院创新性地开展了一个评估工作,目的是研究在25年的建筑发展中原始竞赛作品中的创意是如何实现的。本文采用的数据取自始建于20世纪80年代的15个居民区里的1000～1200个公寓房。本文基于评估得到的临时结果包括在建筑规划和施工阶段把建筑的持续改变能力做到最出色的前6位方案。