中俄木材贸易的新契机

2003年11月2日,我陪同R. E Taylor & Associates公司的高级咨询专家Gerry Van Leeuwen先生对中俄边境城市的木材贸易和加工状况开始了为期一周的参观考察。我们走访的城市包括满洲里、哈尔滨、东宁和绥芬河,共参观了近15家木材加工厂、各地的铁路换装场,以及中俄边境区等。 R. E Taylor & Associates是加拿大著名的林产品咨询公司,为很多著名的美国公司提供咨询服务。他告诉我,目前一些美国公司希望进口俄罗斯木材和木制品,但由于俄罗斯独有的环境和贸易方式,使得他们     

Influence of sulfur amino acids on the volatile and nonvolatile components of cooked salmon (Salmo salar)

Volatile and nonvolatile compounds, which could contribute to flavor, were analyzed in salmon. One hundred twenty-three volatile compounds were identified in the headspace of two different samples of cooked salmon, including lipid-derived volatiles, Maillard-derived volatiles, sulfur volatiles, Strecker aldehydes, nitrogen heterocyclic compounds, terpenes, and trimethylamine. Significant differences between samples were found for 104 of the volatiles. Although the levels of free cysteine and methionine were low in the salmon, sulfur volatiles were formed in the cooked fish, demonstrating that there were sufficient sulfur amino acids present for their formation. Notable differences in sulfur compounds between the samples suggested that small changes in sulfur amino acids could be responsible. When this hypothesis was tested, salmon heated with cysteine had increased levels of many thiophenes, thiazoles, alicyclic sulfides, and nitrogen heterocycles. With the addition of methionine, levels of dimethyl sulfides, two alicyclic sulfides, pyrazines, some unsaturated aldehydes, and alcohols and 2-furanmethanethiol increased. The largest difference found among the nonvolatile (low molecular weight water-soluble) compounds was in inosine monophosphate.     

Corroborative study on maize quality, dry-milling and wet-milling properties of selected maize hybrids

A corroborative study was conducted on the maize quality properties of test weight, pycnometer density, tangential abrasive dehulling device (TADD), time-to-grind on the Stenvert hardness tester (SHT), 100-kernel weight, kernel size distribution, and proximate composition as well as maize dry- and wet-millability by six participating laboratories. Suggested operating procedures were given to compare their measurements and provide the variance structure within and between laboratories and hybrids. Partial correlation coefficient among maize quality properties varied among laboratories. The repeatability and reproducibility precision values were acceptably low for the physical quality tests, except for TADD and SHT time-to-grind measurements. The yields of dry- and wet-milled products and their correlation with maize quality properties were dependent on the collaborating laboratory. This paper highlights the importance of laboratory variation when considering which maize hybrids are best suited for dry-milling and wet-milling.     

Mechanisms of alkylpyrazine formation in a potato model system containing added glycine

The use of glycine to limit acrylamide formation during the heating of a potato model system was also found to alter the relative proportions of alkylpyrazines. The addition of glycine increased the quantities of several alkylpyrazines, and labeling studies using [2-13C]glycine showed that those alkylpyrazines which increased in the presence of glycine had at least one 13C-labeled methyl substituent derived from glycine. The distribution of 13C within the pyrazines suggested two pathways by which glycine, and other amino acids, participate in alkylpyrazine formation, and showed the relative contribution of each pathway. Alkylpyrazines that involve glycine in both formation pathways displayed the largest relative increases with glycine addition. The study provided an insight into the sensitivity of alkylpyrazine formation to the amino acid composition in a heated food and demonstrated the importance of those amino acids that are able to contribute an alkyl substituent. This may aid in estimating the impact of amino acid addition on pyrazine formation, when amino acids are added to foods for acrylamide mitigation.     

Breast-feeding in a UK urban context: who breast-feeds, for how long and does it matter?

OBJECTIVE: To investigate what factors relate most strongly to breast-feeding duration in order to successfully support breast-feeding mothers. DESIGN: Prospective birth cohort study using questionnaires, routinely collected weights and health check at age 13 months. SETTING: Gateshead, UK. SUBJECTS: Parents of 923 term infants born in a defined geographical area and recruited shortly after birth, 50% of whom were breast-feeding initially. RESULTS: Only 225 (24%) infants were still breast-fed at 6 weeks, although 136 (15%) continued beyond 4 months. Infants in the most affluent quintile were three times more likely to be initially breast-fed (P < 0.001) and five times more likely to still be feeding at 4 months (P = 0.001) compared with infants in the most deprived quintile. A third of breast-fed infants were given supplementary feeds in the maternity unit and this was associated with a 10-fold increase in odds of giving up breast-feeding by discharge (P = 0.001). Frequent feeding was reported as a reason for giving up in 70% of mothers at 6 weeks and 55% at 4 months. Those infants who stopped breast-feeding earliest showed the most rapid weight gain and were tallest at age 13 months. Non-breast-fed infants had 50% more family doctor contacts up to age 4 months (P = 0.005). CONCLUSIONS: Initiation of breast-feeding in urban Britain remains strongly determined by socio-economic background and early cessation seems to be related to frequent feeding and rapid growth as well as a continuing failure to eradicate health practices that undermine breast-feeding. Those infants not receiving breast milk suffered increased morbidity, but the apparent association between breast-feeding duration and growth probably reflects reverse causation.     

Do mothers understand healthy eating principles for low-birth-weight infants?

OBJECTIVES: To describe feeding patterns and mothers' perceptions of desirable feeding practices in low-birth-weight (LBW) infants after hospital discharge in England and to test for the association of inappropriate practices/perceptions with identifiable demographics. DESIGN: Postal questionnaires from 198 mothers of LBW infants in London, Liverpool and Winchester were analysed regarding infant demographics, mothers' demographics, infant milks used, solid feeding practices and mothers' perceptions of infant feeding practices. RESULTS: At birth, the median weight, independent of gestational age, was 1.80 kg (range 0.6-2.50 kg) and 37.1% of infants received breast milk exclusively; 83.7% were breast-fed at some stage, a practice favoured more by first-time mothers (90.2%) than multiparous mothers (73.4%) (P = 0.004) as well as by mothers of higher social groups (P = 0.019). The median age of solid food introduction was 17 postnatal weeks (range 8-36 weeks); the timing correlated strongly with infant birth weight (P < 0.001). A high-fibre diet and a low-fat diet were incorrectly considered important for their infants by 67.1% and 51.6% of mothers, respectively. Regarding a high-fibre diet as important was associated with being a multiparous mother (P = 0.006), while regarding a low-fat diet as important was associated with low social group (P = 0.018). A quarter of mothers did not consider 'plenty of calories' to be important for their infants, reflecting similar attitudes in 1990 for mothers of term infants; this incorrect attitude exhibited an association with being a first-time mother (P = 0.047). CONCLUSIONS: Infant feeding practices were very variable, showing poor concordance with national and international recommendations for term infants. In selecting foods for their infants, many mothers appeared to be applying principles more appropriate to planning a healthy diet for adults. There is an urgent need to develop and implement evidence-based guidelines for feeding LBW infants after hospital discharge, with special attention given to multiparous mothers as well as mothers from lower social groups.     

Effect of positive end-expiratory pressure on oxygen delivery during 1-lung ventilation for thoracoscopy in normal dogs

OBJECTIVE: To evaluate the effect of positive end-expiratory pressure (PEEP) on oxygen delivery (DO(2)) with 1-lung ventilation during thoracoscopy in normal anesthetized dogs. STUDY DESIGN: Prospective, controlled experimental study. ANIMALS: Eight, adult, intact Walker Hound dogs weighing 25.6-29.2 kg. METHODS: Anesthetized dogs had 1-lung ventilation during an open-chest condition. A Swan-Ganz catheter was used to measure pulmonary hemodynamic variables and to obtain mixed venous blood samples for blood gas analysis. A dorsal pedal catheter was used for measurement of systemic arterial pressure and to obtain arterial blood samples for blood gas analysis. Oxygen delivery was calculated and used to assess the effect of 0, 2.5, and 5 cm H(2)O PEEP during 1-lung ventilation on cardiopulmonary function. Each dog was its own control at 0 cm H(2)O PEEP. A randomized block ANOVA for repeated measures was used to evaluate the effect of the treatment on hemodynamic and pulmonary variables. RESULTS: Use of 5 cm H(2)O PEEP induced a significant augmentation in the arterial partial pressure of oxygen (PaO(2)). Shunt fraction (Q(s)/Q(t)), physiologic dead space (V(D)/V(T)), and the alveolar-arterial oxygen difference (P(A-a)O(2)) decreased significantly after 5 cm H(2)O PEEP, compared with 1-lung ventilation without PEEP. Use of 2.5 cm H(2)O PEEP had no significant effect on cardiopulmonary variables. Use of PEEP had no significant effect on arterial oxygen saturation (SaO(2)), DO(2), and hemodynamic variables in normal dogs. CONCLUSIONS: PEEP had no effect on DO(2) in normal dogs undergoing open-chest 1-lung ventilation because it had no adverse effect on hemodynamic variables. CLINICAL RELEVANCE: PEEP in normal dogs during open-chest 1-lung ventilation for thoracoscopy is not detrimental to cardiac output and can be recommended in clinical patients.     

Characterization of a Novel Resistant‐Starch and Its Effects on Postprandial Plasma‐Glucose and Insulin Responses

Objectives of this study were to understand the physicochemical properties of a novel resistant starch (RS) made by complexing high‐amylose maize starch VII (HA7) with palmitic acid (PA), and its effects on reducing postprandial plasma‐glucose and insulin responses. The HA7 starch was heat‐treated and debranched using isoamylase (ISO) to enhance the starch‐lipid complex formation. The RS content of the HA7 starch debranched with ISO and complexed with PA (HA7+ISO+PA) was 52.7% determined using AOAC Method 991.43 for dietary fiber, which was greater than that of the HA7 control (35.4%). The increase in the RS content of the HA7+ISO+PA sample was attributed to the formation of retrograded debranched‐starch and starch‐lipid complex. The postprandial plasma‐glucose and insulin responses of 20 male human‐subjects after ingesting bread made from 60% (dry basis) HA7+ISO+PA were reduced to 55 and 43%, respectively, when compared with those after ingesting control white bread (as 100%) containing the same amount of total carbohydrates. The results suggested that the HA7+ISO+PA can be used for the interventions of insulin resistance and metabolic syndrome, including diabetes and obesity.     

The robustness and restoration of a network of ecological networks

Understanding species' interactions and the robustness of interaction networks to species loss is essential to understand the effects of species' declines and extinctions. In most studies, different types of networks (such as food webs, parasitoid webs, seed dispersal networks, and pollination networks) have been studied separately. We sampled such multiple networks simultaneously in an agroecosystem. We show that the networks varied in their robustness; networks including pollinators appeared to be particularly fragile. We show that, overall, networks did not strongly covary in their robustness, which suggests that ecological restoration (for example, through agri-environment schemes) benefitting one functional group will not inevitably benefit others. Some individual plant species were disproportionately well linked to many other species. This type of information can be used in restoration management, because it identifies the plant taxa that can potentially lead to disproportionate gains in biodiversity.