Experimental Study of Stress Effects on the Degradation Rate in vitro of Novel Magnesium Alloy Bone Screws / 医用生物力学

Objective To study the effect of stress on the degradation rate in vitro of novel magnesium alloy bone screw. Methods A three-dimensional （3D） model of the tibia fracture was established using the reverse engineering method. Then, based on the FE model, the in vitro degradation experimental device for bone screws was designed. The stress distribution of the screw by finite element calculation was used as the in vitro experimental load, which effectively improved the accuracy and efficiency of the experiment. The experimental samples were divided into four groups. Group A was treated as control group without force application, while Groups B, C and D were subjected to 150, 250 and 350 N axial forces. The influence of different mechanical environment on the degradation rate in vitro of bone screws was investigated. Finally, combining the stress distributions with the degradation experiment results in vitro, the curve between the stress and the degradation rate in vitro of novel magnesium alloy bone screws was obtained. Results Degradation experiments in vitro showed that Group A had the lowest weight loss and hydrogen production, and the average degradation rate was (0.315±0.005) mm/a. While in the stress groups, the weight loss and hydrogen production increased gradually with the axial force increasing. The average degradation rates of Groups B, C and D were (0.379±0.006), (0.469±0.007) and (0.547±0.009) mm/a, respectively. Conclusions When the novel magnesium alloy bone screw was degraded in mechanical environment, the greater stress on the screw would cause the faster degradation rate in vitro. The obtained relationship between the maximum stress and the average degradation rate in vitro of the novel megnesium alloy bone screw provided data support and theoretical guidance for material selection, design and clinical application of magnesium alloy bone screws.

Analysis on High Purity Magnesium Bone Screws in vivo / 医用生物力学

Objective To compare the in vivo degradation rates of two different kinds of high purity magnesium bone screws by animal experiments, so as to make some suggestions on structural design of high purity magnesium bone screws. Methods High purity magnesium bone screws with threads and without threads were implanted into femoral condyles of New Zealand rabbits separately. Twenty-four rabbits were randomly divided into 3 groups. They were euthanized at 8, 12 and 16 weeks after operation, respectively. The in vivo degradation rates of bone screws with two different shapes were compared through micro-CT scanning and Skyscan CT-analyser software, and the stress changes during the progress of bone screw degradation were analyzed. Results The initial surface area of threaded screws ［(31.70±0.06) mm2］ was significantly greater than that of the non-threaded ones ［(29.56±0.22) mm2］. After 8, 12 and 16 weeks, the volume loss ratios of the threaded screws were (26.01±3.44)%, (33.35±5.05)%, (36.84±6.99)%, respectively, and the volume loss ratios of the non-threaded screws were (22.53±4.78)%, (31.12±6.59)%, (43.22±9.31)%, respectively. At the same time point, there were no significant differences in the volume loss ratio between two kinds of screws. The relationship between the volume reduction and the implantation time was linear for non-threaded screws and gradually decreasing for threaded screws. Conclusions Under the low-bearing condition, different structural design for high purity magnesium screws has no obvious effect on their degradation rate in vivo.

The Analysis of the Accelerated Degradation Test for Protein-type Biological Standard Substances / 中国药学杂志

OBJECTIVE: To establish a weighted least square method for the accelerated degradation analysis of protein-type biological standard substances.METHODS: A mathematical model was proposed to estimate the parameters of degradation rate constants k at the elevated temperatures based on the Arrhenius or Eyring equation and chemical reaction principles under the suitable assumptions. Hence, it is probably to predict the stability of biological standard at the normal condition by solving the model.RESULTS: According to the experimental data of recombinant human granulocyte colony-stimulating factor and interferon α-2a, the preliminary numerical experiments were also performed and the results confirm the reliability of the method in the paper.CONCLUSION: The same methodology may be applied in the pharmaceutical industry where it is necessary to predict the viable shelf-life of biological products.

Fracionamento de carboidratos e proteínas, cinética de degradação ruminal in vitro pela técnica de produção de gás, de rações suplementares contendo torta de girassol / Fractionation of carbohydrates, protein and "in vitro" ruminal degradation kinetics by gas production technique of supplementary rations containing sunflower cake

Objetivou-se neste estudo fracionar os carboidratos e as proteínas e avaliar a cinética de degradação ruminal de rações contendo 0; 24; 48 e 72% de torta de girassol. Os carboidratos foram fracionados em A+B1, B2 e C, e as proteínas em A, B1+B2, B3 e C. Os parâmetros de cinética de degradação ruminal das rações foram estimados a partir do método semiautomático de produção cumulativa de gases in vitro. Foram utilizados quatro animais 1/2 Gir x 1/2 Holandês, machos e castrados, fistulados no rúmen, mantidos em pastagem e recebendo 1kg de ração concentrada, como doadores de inócuo ruminal. O ensaio foi realizado em delineamento em blocos ao acaso, com quatro rações e quatro períodos, e os resultados obtidos foram interpretados de acordo com a análise de variância e de regressão a 5% de significância. Houve efeito linear decrescente para o fracionamento de carboidratos totais e a fração A+B1, e efeito linear crescente sobre as frações B2 e C. Para as frações nitrogenadas, houve efeito linear crescente sobre a fração A, e efeito linear decrescente sobre as frações B1+B2 e C. Em relação à cinética de degradação ruminal in vitro, houve efeito decrescente sobre o parâmetro "a", e efeito quadrático sobre os parâmetros "b" e "c", com pontos de máxima, respectivamente, de 61,84 e 66,77% de torta de girassol. A inclusão da torta de girassol nas rações suplementares, nos teores estudados, influenciou nas frações dos carboidratos, das proteínas e nos parâmetros de degradação ruminal. Caso haja a disponibilidade desse ingrediente, ele pode ser adicionado à ração suplementar de bovinos sem prejuízo nos parâmetros nutricionais e metabólicos.(AU)

This work aimed to fractionate carbohydrates and protein and to evaluate ruminal degradation kinetics of rations containing 0; 24; 48 and 72% of inclusion of sunflower cake. The carbohydrates were fractionate in A+B1, B2 and C fraction, and protein in A, B1+B2, B3 and C. Rations ruminal degradation kinetics were realized with the "in vitro" semiautomatic gas production technique. Four male, castrated, 1/2 Gir x 1/2 Holstein were used, all of them fistulated in the rumen. This study was done in randomized block design with four rations and four periods. The results obtained were interpreted according to variance and regression analysis at 5% significance level. There is a decreasing effect for total carbohydrates fractionation and A+B1 fraction, and there is an increasing effect for B2 and C fraction. For nitrogen fractions there is an increasing effect on fraction A and negative linear effect on B1+B2 and C fractions. For "In vitro" ruminal degradation kinetics there is a decreasing effect for "a" parameter, and quadratic effect for "b" and "c" parameters with maximum points respectively 61.84 and 66.77% of sunflower seed meal. The inclusion of sunflower cake in supplementary feeding, the studied levels, influenced the fractions of carbohydrates, proteins and degradation parameters. If there is the availability of this ingredient, it can be added to the supplemental feed cattle subject to the nutritional and metabolic parameters.(AU)

Degradation rates and products of fluticasone propionate in alkaline solutions / 药物分析学报

The apparent degradation rate constant of fluticasone propionate (FLT) in 0.1 M NaOH:methanol=1:1 at 37 ℃ was previously reported to be 0.169 ± 0.003 h?1, and four degradation products (products 1–4) were observed in the solution. The aims of the present study were to assess the degradation rates of FLT in other alkaline solutions and clarify the chemical structures of the four degradation products in order to obtain basic data for designing an enema for inflammatory bowel disease. The apparent degradation rate constants in 0.05 M NaOH and 0.1 M NaOH:CH3CN=1:1 were 0.472 ± 0.013 h?1 and 0.154 ± 0.000 h?1 (n=3), respectively. The chemical structures of products 1–4 in 0.1 M NaOH:methanol=1:1 were revealed by nuclear magnetic resonance (NMR) and mass spectrometry data. The chemical structure of products 2 was that the 17-position of the thioester moiety of FLT was substituted by a carboxylic acid. The degradation product in 0.1 M NaOH:CH3CN=1:1 was found to be product 2 based on 1H NMR data. The degradation product in 0.05 M NaOH was considered to be product 2 based on the retention time of HPLC. These results are useful for detecting the degradation products of FLT by enzymes of the intestinal bacterial flora in the large intestine after dosing FLT as an enema.

Degradation rates and products of fluticasone propionate in alkaline solutions / 药物分析学报

The apparent degradation rate constant of fluticasone propionate (FLT) in 0.1 M NaOH:methanol=1:1 at 37 ℃ was previously reported to be 0.169 ± 0.003 h?1, and four degradation products (products 1–4) were observed in the solution. The aims of the present study were to assess the degradation rates of FLT in other alkaline solutions and clarify the chemical structures of the four degradation products in order to obtain basic data for designing an enema for inflammatory bowel disease. The apparent degradation rate constants in 0.05 M NaOH and 0.1 M NaOH:CH3CN=1:1 were 0.472 ± 0.013 h?1 and 0.154 ± 0.000 h?1 (n=3), respectively. The chemical structures of products 1–4 in 0.1 M NaOH:methanol=1:1 were revealed by nuclear magnetic resonance (NMR) and mass spectrometry data. The chemical structure of products 2 was that the 17-position of the thioester moiety of FLT was substituted by a carboxylic acid. The degradation product in 0.1 M NaOH:CH3CN=1:1 was found to be product 2 based on 1H NMR data. The degradation product in 0.05 M NaOH was considered to be product 2 based on the retention time of HPLC. These results are useful for detecting the degradation products of FLT by enzymes of the intestinal bacterial flora in the large intestine after dosing FLT as an enema.

Fontes proteicas alternativas oriundas da cadeia produtiva do biodiesel para alimentação de ruminantes / Alternative protein sources derived from the biodiesel production chain for feeding to ruminants

Objetivou-se avaliar a degradação e a produção de gás de diferentes fontes proteicas geradas na cadeia produtiva do biodiesel em substituição à silagem de milho. Os tratamentos foram: coprodutos de Gossyypium hirsutum, Ricinus communis, Moringa oleifera, Jatropha curcas, Helianthus annus. Os produtos foram analisados mediante a técnica semiautomática de produção de gases in vitro. O coproduto da moringa apresentou maior taxa de degradação, quando comparado aos demais alimentos, porém apresentou baixa produção de gás e se tornou mais eficiente, sendo, portanto, indicado como o melhor nível (27,06%) de substituição à silagem de milho. O coproduto da mamona e o do algodão produziram a maior quantidade de gás em 48h de incubação. Todos os coprodutos estudados podem ser utilizados na dieta de ruminantes como alimento proteico até 30% de substituição à silagem de milho.(AU)

This study aimed to assess the degradation and gas production of different protein sources generated in the biodiesel production chain replacing corn silage. The treatments were byproducts Gossyypium hirsutum, Ricinus communis, Moringa oleifeira, Jatrophacurcas, and Helianthusannus. The products were analyzed by semi-automated technique of gas production in vitro. The coproduct moringa showed higher degradation rate compared to other foods, but showed low gas production, making it more efficient, being nominated as the best level of 27.06% by replacing corn silage. The byproducts of castor oil and cottonseed produced the largest amount of gas in 48 h of incubation. All studied byproducts can be used in the diet of ruminants as a protein food up to 30% by substitution of corn silage.(AU)

Fertility status, Degradation Rate and Vulnerability Potential of Soils of Sowa Chiefdom in Southern Sierra Leone.

The present research was undertaken to study the fertility status of physicochemical properties and assess the degradation rate and vulnerability potential of soils of Sowa Chiefdom and suggest best management practices. Thirty-two composite samples from 0-20 and 20-40 cm were collected at fifteen locations and studied. The soils exhibited an irregular trend in particle size distribution with high proportion of sand in decreasing trend of sandy loam > sandy clay loam > loamy sand > sandy clay > clay. The soils were slightly acidic to moderately acidic in soil reaction (soil pH) with low to high organic carbon, medium to high nitrogen and low to high phosphorus. The content of exchangeable Ca2+ was medium to high, exchangeable Mg2+ was high, exchangeable Na+ was low to high and exchangeable K+ was low. The level of exchangeable acidity was low although the pH was slight to moderately acidic. The effective CEC values were within themedium to high range and the base saturation was high, thus indicating the potential availability of basic elements in the soils. The organic carbon, total nitrogen, available phosphorus, exchangeable Ca and Mg and base saturation were neither degraded nor vulnerable to degradation and therefore better soil quality indicators while exchangeable K was extremely degraded and highly vulnerable to degradation and therefore a poor soil quality indicator. The texture, soil pH, exchangeable Na and effective CEC showed moderate rate of degradation and vulnerability and these might be good soil quality indicators in the long term if the recommended soil management strategies are adopted.

Evaluation of biological removal efficiency in an UCT process treating municipal wastewater during start-up stage.

This study reports the performance of University of Cape Town (UCT) municipal wastewater treatment plant, during the startup stage with the focus on the relationship between hydraulic retention time (HRT) and biological nutrient removal (BNR) efficiency. The entire experimental period was 144 days, divided into four periods. Results showed that the removal efficiency of TN, NH4+-N, and Kjeldahl nitrogen (KN) was closely related to the HRT. Furthermore, the biodegradation kinetics analysis was used to calculate the specific degradation rates of pollutants. The GPS-X modeling was also used to examine the effect of the UCT pilot plant on BNR. The UCT pilot plant used in this study achieved high BNR efficiency even during the startup stage. With HRT of 24 hr (Period 1, day 1-40, data set 1-10), the highest levels of TN, NH4+-N and KN removal efficiency were approximately 72, 76 and 78%, respectively. The COD showed consistent high removal efficiency, with the highest level of approximately 96% at HRT of 15 hr (Period 3, day 81-120, data set 21-30). The TP removal efficiency rose at first and subsequently decreased abruptly. The maximum removal efficiency was 85% with HRT of 19 hr (Period 2, day 41-80, data set 11-20). With the optimal HRT 19 hr, the average removal efficiency values of COD, TP, TN, NH4+-N and KN were 89, 80, 65, 67 and 68%, respectively. The GPS-X modeling results indicated that the UCT process was effective in COD, TP and TN removal.

Degradabilidade in situ do rolão e farelo de milho em caprinos e ovinos deslanados mantidos em sombra natural e artificial no semi-árido paraibano / Degradability in situ of ground cob corn and corn (maize) bran in goats and wooless sheep kept in natural and artificial shade in the semi-arid region of Paraíba

Objetivou-se, com este trabalho, avaliar a degradabilidade "in situ" do rolão de milho e do farelo de milho em caprinos e ovinos deslanados, mantidos em ambientes de sombra natural e artificial, no Semiárido paraibano. Foram utilizados quatro caprinos e quatro ovinos distribuídos em dois ambientes, um natural e outro artificial. Foram incubados sacos de náilon, contendo amostras do rolão e farelo de milho nos tempos de 6, 12, 24 e 48 e 72 horas para o alimento volumoso e 6, 12, 24, 48 horas para o concentrado. Os efeitos dos ambientes e das espécies na fração b e c da MS no rolão de milho foram independentes. No ambiente artificial, a média da degradabilidade da fração b (55,36 por cento) foi superior à média obtida no ambiente natural (50,97 por cento) e a fração c apresentou maior valor no ambiente natural (40,90 por cento) do que o artificial (36,51 por cento). Quanto à fração b e c da MS do farelo de milho, não houve interação entre espécies e ambientes, a degradabilidade da fração b da MS para a espécie caprina foi superior à ovina com 60,77 por cento e 56,47 por cento, respectivamente. Ocorrendo o inverso para a fração c, onde os ovinos apresentaram média superior aos caprinos (31,93 e 27,63 por cento). Houve efeito da ambiente para a DP da MS do rolão de milho, os valores da fração b no ambiente natural e artificial foram (50,97 e 55,36 por cento) respectivamente. A DP da MS do farelo de milho para a espécie caprina foi maior do que para a espécie ovina (72,37 e 68,07 por cento, respectivamente). A degradabilidade efetiva a 5 por cento da MS foi maior para caprinos (31,17 por cento) do que para ovinos (28,48 por cento). A DE da MS (calculada com taxa de passagem de 2 e 5 por cento/ h) do farelo de milho para a espécie caprina foi superior (60,34 e 49,18 por cento) a da ovina (56,88 e 46,51 por cento, respectivamente). Concluiu-se que tanto a espécie como o ambiente influenciam na degradabilidade dos alimentos. Os ovinos e caprinos ...

The objective of this study was to evaluate "in situ" degradability of ground cob corn and corn (maize) bran in goats and wooless sheep kept in natural and artificial shade environments in the semi-arid region of Paraíba. Four goats and four sheep were used, being distributed in two environments, one natural and the other artificial. Nylon sacks were incubated containing samples of ground cob corn and corn (maize) bran in intervals of 6, 12, 24, 48, and 72 hours for the bulk food, and 6, 12, 24, and 48 hours for the concentrate. The effects of the environments and of the species in fractions b and c of dry matter in the cob corn were independent. In the artificial environment, the average of the degradability of fraction b (55,36 percent) was higher than the average obtained in the natural environment (50,97 percent); and fraction c presented a higher value in the natural environment (40,90 percent) than in the artificial (36,51). With respect to fractions b and c of the dry matter of the corn bran, there was no interaction between species and environments; and the degradability of fraction b of dry matter for the goats was higher than for the sheep, with 60,77 percent and 56,47 percent, respectively. With respect to fraction c, the inverse was verified. The sheep presented a higher average than the goats (31,93 and 27,63 percent). There was environmental effect for potential degradability of dry matter of the cob corn. The values of fraction b in the natural and artificial environments were 50,97 and 55,36 percent, respectively. The potential degradability of corn bran for the goats was higher than for the sheep (72,37 and 68,07 percent, respectively). The effective degradability to 5 percent of the dry matter was higher for the goats (31,17 percent) than for the sheep (28,48 percent). The effective degradability of the dry matter (calculated with passage rate of 2 and 5 percent/h) of the corn bran for the goats was superior (60,34 and ...

Dinâmicas de trânsito e degradação da fibra em detergente neutro em bovinos alimentados com forragem tropical de baixa qualidade e compostos nitrogenados / Transit and degradation dynamics of neutral detergent fiber in cattle fed low-quality tropical forage and nitrogenous compounds

Avaliaram-se as dinâmicas de trânsito e degradação da fibra em detergente neutro (FDN) em bovinos alimentados com forragem tropical de baixa qualidade e compostos nitrogenados. Foram utilizadas cinco novilhas Holandês x Zebu fistuladas no rúmen. A alimentação volumosa basal dos animais foi constituída por feno de capim-braquiária (Brachiaria decumbens Stapf.), com 5,08 por cento de proteína bruta (PB), com base na matéria seca (MS), fornecido ad libitum. Os cinco tratamentos avaliados foram definidos de acordo com o nível de suplementação proteica (0, 3, 5, 7 e 9 pontos percentuais acima do nível de PB da forragem). Como fonte de compostos nitrogenados, empregou-se mistura de ureia:sulfato de amônia:albumina (4,5:0,5:1,0). O experimento foi estruturado segundo delineamento em quadrado latino 5 x 5. Os níveis médios de PB nas dietas foram de 5,28; 8,08; 9,82; 11,87 e 13,63 por cento, com base na MS. Verificou-se elevação linear (P<0,05) da fração potencialmente degradável da FDN até o nível de 8,62 por cento de PB, com platô estimado de 47,92 por cento da FDN. Verificou-se efeito quadrático (P<0,05) sobre a taxa de degradação da fração potencialmente degradável da FDN em função dos níveis de PB da dieta, com máxima resposta estimada sobre 13,39 por cento de PB. O fluxo ruminal de partículas fibrosas apresentou relação linear-response-plateau em função do nível de PB na dieta (P<0,05), com ponto crítico para o início do platô sobre 7,59 por cento de PB.

Rumen transit and degradation dynamics of neutral detergent fiber (NDF) in cattle fed low-quality tropical forage and nitrogenous compounds were evaluated. Five crossbred heifers fitted with rumen cannulae were used. The animals were fed ad libitum with signal grass (Brachiaria decumbens Stapf.) hay, which had crude protein (CP) content of 5.08 percent in dry matter (DM). The five treatments were defined according to the level of CP in the diet (0, 3, 5, 7, and 9 percentile points above the CP level of the roughage). The supplement was a mixture of urea, ammonium sulfate, and albumin (4.5:0.5:1.0, respectively). The experiment was carried out according to a 5 x 5 Latin square design. The average CP levels in the diets were: 5.28, 8.08, 9.82, 11.87, and 13.63 percent in DM basis. The potentially degradable fraction of NDF was linearly increased (P<0.05) by CP levels in diet until 8.62 percent CP. From this point, there was stabilization of estimates (47.92 percent of NDF). The degradation rate of potentially degradable NDF showed a quadratic response (P<0.05) to CP levels, with maximal response at 13.39 percent of CP. The ruminal rate of passage of fibrous particles showed a linear-response-plateau (P<0.05) according to CP levels in the diet, with plateau beginning at 7.59 percent of CP.